1 /*************************************************
2 * Exim - an Internet mail transport agent *
3 *************************************************/
5 /* Copyright (c) University of Cambridge 1995 - 2018 */
6 /* See the file NOTICE for conditions of use and distribution. */
8 /* Copyright (c) Phil Pennock 2012 */
10 /* This file provides TLS/SSL support for Exim using the GnuTLS library,
11 one of the available supported implementations. This file is #included into
12 tls.c when USE_GNUTLS has been set.
14 The code herein is a revamp of GnuTLS integration using the current APIs; the
15 original tls-gnu.c was based on a patch which was contributed by Nikos
16 Mavrogiannopoulos. The revamp is partially a rewrite, partially cut&paste as
19 APIs current as of GnuTLS 2.12.18; note that the GnuTLS manual is for GnuTLS 3,
20 which is not widely deployed by OS vendors. Will note issues below, which may
21 assist in updating the code in the future. Another sources of hints is
22 mod_gnutls for Apache (SNI callback registration and handling).
24 Keeping client and server variables more split than before and is currently
25 the norm, in anticipation of TLS in ACL callouts.
27 I wanted to switch to gnutls_certificate_set_verify_function() so that
28 certificate rejection could happen during handshake where it belongs, rather
29 than being dropped afterwards, but that was introduced in 2.10.0 and Debian
30 (6.0.5) is still on 2.8.6. So for now we have to stick with sub-par behaviour.
32 (I wasn't looking for libraries quite that old, when updating to get rid of
33 compiler warnings of deprecated APIs. If it turns out that a lot of the rest
34 require current GnuTLS, then we'll drop support for the ancient libraries).
37 #include <gnutls/gnutls.h>
38 /* needed for cert checks in verification and DN extraction: */
39 #include <gnutls/x509.h>
40 /* man-page is incorrect, gnutls_rnd() is not in gnutls.h: */
41 #include <gnutls/crypto.h>
43 /* needed to disable PKCS11 autoload unless requested */
44 #if GNUTLS_VERSION_NUMBER >= 0x020c00
45 # include <gnutls/pkcs11.h>
46 # define SUPPORT_PARAM_TO_PK_BITS
48 #if GNUTLS_VERSION_NUMBER < 0x030103 && !defined(DISABLE_OCSP)
49 # warning "GnuTLS library version too old; define DISABLE_OCSP in Makefile"
52 #if GNUTLS_VERSION_NUMBER < 0x020a00 && !defined(DISABLE_EVENT)
53 # warning "GnuTLS library version too old; tls:cert event unsupported"
54 # define DISABLE_EVENT
56 #if GNUTLS_VERSION_NUMBER >= 0x030306
57 # define SUPPORT_CA_DIR
59 # undef SUPPORT_CA_DIR
61 #if GNUTLS_VERSION_NUMBER >= 0x030014
62 # define SUPPORT_SYSDEFAULT_CABUNDLE
64 #if GNUTLS_VERSION_NUMBER >= 0x030104
65 # define GNUTLS_CERT_VFY_STATUS_PRINT
67 #if GNUTLS_VERSION_NUMBER >= 0x030109
70 #if GNUTLS_VERSION_NUMBER >= 0x03010a
71 # define SUPPORT_GNUTLS_SESS_DESC
73 #if GNUTLS_VERSION_NUMBER >= 0x030500
74 # define SUPPORT_GNUTLS_KEYLOG
76 #if GNUTLS_VERSION_NUMBER >= 0x030506 && !defined(DISABLE_OCSP)
77 # define SUPPORT_SRV_OCSP_STACK
79 #if GNUTLS_VERSION_NUMBER >= 0x030603
80 # define EXIM_HAVE_TLS1_3
81 # define SUPPORT_GNUTLS_EXT_RAW_PARSE
82 # define GNUTLS_OCSP_STATUS_REQUEST_GET2
86 # if GNUTLS_VERSION_NUMBER >= 0x030000
87 # define DANESSL_USAGE_DANE_TA 2
88 # define DANESSL_USAGE_DANE_EE 3
90 # error GnuTLS version too early for DANE
92 # if GNUTLS_VERSION_NUMBER < 0x999999
93 # define GNUTLS_BROKEN_DANE_VALIDATION
97 #ifdef EXPERIMENTAL_TLS_RESUME
98 # if GNUTLS_VERSION_NUMBER < 0x030603
99 # error GNUTLS version too early for session-resumption
104 # include <gnutls/ocsp.h>
107 # include <gnutls/dane.h>
110 #include "tls-cipher-stdname.c"
117 # ifdef EXPERIMENTAL_TLS_RESUME
118 builtin_macro_create_var(US"_RESUME_DECODE", RESUME_DECODE_STRING );
120 # ifdef EXIM_HAVE_TLS1_3
121 builtin_macro_create(US"_HAVE_TLS1_3");
130 gnutls_global_set_audit_log_function()
133 gnutls_certificate_verify_peers2(): is new, drop the 2 for old version
136 /* Local static variables for GnuTLS */
138 /* Values for verify_requirement */
140 enum peer_verify_requirement
141 { VERIFY_NONE, VERIFY_OPTIONAL, VERIFY_REQUIRED, VERIFY_DANE };
143 /* This holds most state for server or client; with this, we can set up an
144 outbound TLS-enabled connection in an ACL callout, while not stomping all
145 over the TLS variables available for expansion.
147 Some of these correspond to variables in globals.c; those variables will
148 be set to point to content in one of these instances, as appropriate for
149 the stage of the process lifetime.
151 Not handled here: global tls_channelbinding_b64.
154 typedef struct exim_gnutls_state {
155 gnutls_session_t session;
156 gnutls_certificate_credentials_t x509_cred;
157 gnutls_priority_t priority_cache;
158 enum peer_verify_requirement verify_requirement;
161 BOOL peer_cert_verified;
162 BOOL peer_dane_verified;
163 BOOL trigger_sni_changes;
164 BOOL have_set_peerdn;
165 const struct host_item *host; /* NULL if server */
166 gnutls_x509_crt_t peercert;
169 uschar *received_sni;
171 const uschar *tls_certificate;
172 const uschar *tls_privatekey;
173 const uschar *tls_sni; /* client send only, not received */
174 const uschar *tls_verify_certificates;
175 const uschar *tls_crl;
176 const uschar *tls_require_ciphers;
178 uschar *exp_tls_certificate;
179 uschar *exp_tls_privatekey;
180 uschar *exp_tls_verify_certificates;
182 uschar *exp_tls_require_ciphers;
183 const uschar *exp_tls_verify_cert_hostnames;
184 #ifndef DISABLE_EVENT
185 uschar *event_action;
188 char * const * dane_data;
189 const int * dane_data_len;
192 tls_support *tlsp; /* set in tls_init() */
197 BOOL xfer_eof; /*XXX never gets set! */
199 } exim_gnutls_state_st;
201 static const exim_gnutls_state_st exim_gnutls_state_init = {
202 /* all elements not explicitly intialised here get 0/NULL/FALSE */
207 /* Not only do we have our own APIs which don't pass around state, assuming
208 it's held in globals, GnuTLS doesn't appear to let us register callback data
209 for callbacks, or as part of the session, so we have to keep a "this is the
210 context we're currently dealing with" pointer and rely upon being
211 single-threaded to keep from processing data on an inbound TLS connection while
212 talking to another TLS connection for an outbound check. This does mean that
213 there's no way for heart-beats to be responded to, for the duration of the
215 XXX But see gnutls_session_get_ptr()
218 static exim_gnutls_state_st state_server;
220 /* dh_params are initialised once within the lifetime of a process using TLS;
221 if we used TLS in a long-lived daemon, we'd have to reconsider this. But we
222 don't want to repeat this. */
224 static gnutls_dh_params_t dh_server_params = NULL;
226 static int ssl_session_timeout = 7200; /* Two hours */
228 static const uschar * const exim_default_gnutls_priority = US"NORMAL";
230 /* Guard library core initialisation */
232 static BOOL exim_gnutls_base_init_done = FALSE;
235 static BOOL gnutls_buggy_ocsp = FALSE;
236 static BOOL exim_testharness_disable_ocsp_validity_check = FALSE;
239 #ifdef EXPERIMENTAL_TLS_RESUME
240 static gnutls_datum_t server_sessticket_key;
243 /* ------------------------------------------------------------------------ */
246 #define MAX_HOST_LEN 255
248 /* Set this to control gnutls_global_set_log_level(); values 0 to 9 will setup
249 the library logging; a value less than 0 disables the calls to set up logging
250 callbacks. GNuTLS also looks for an environment variable - except not for
251 setuid binaries, making it useless - "GNUTLS_DEBUG_LEVEL".
252 Allegedly the testscript line "GNUTLS_DEBUG_LEVEL=9 sudo exim ..." would work,
253 but the env var must be added to /etc/sudoers too. */
254 #ifndef EXIM_GNUTLS_LIBRARY_LOG_LEVEL
255 # define EXIM_GNUTLS_LIBRARY_LOG_LEVEL -1
258 #ifndef EXIM_CLIENT_DH_MIN_BITS
259 # define EXIM_CLIENT_DH_MIN_BITS 1024
262 /* With GnuTLS 2.12.x+ we have gnutls_sec_param_to_pk_bits() with which we
263 can ask for a bit-strength. Without that, we stick to the constant we had
265 #ifndef EXIM_SERVER_DH_BITS_PRE2_12
266 # define EXIM_SERVER_DH_BITS_PRE2_12 1024
269 #define expand_check_tlsvar(Varname, errstr) \
270 expand_check(state->Varname, US #Varname, &state->exp_##Varname, errstr)
272 #if GNUTLS_VERSION_NUMBER >= 0x020c00
273 # define HAVE_GNUTLS_SESSION_CHANNEL_BINDING
274 # define HAVE_GNUTLS_SEC_PARAM_CONSTANTS
275 # define HAVE_GNUTLS_RND
276 /* The security fix we provide with the gnutls_allow_auto_pkcs11 option
277 * (4.82 PP/09) introduces a compatibility regression. The symbol simply
278 * isn't available sometimes, so this needs to become a conditional
279 * compilation; the sanest way to deal with this being a problem on
280 * older OSes is to block it in the Local/Makefile with this compiler
282 # ifndef AVOID_GNUTLS_PKCS11
283 # define HAVE_GNUTLS_PKCS11
284 # endif /* AVOID_GNUTLS_PKCS11 */
290 /* ------------------------------------------------------------------------ */
291 /* Callback declarations */
293 #if EXIM_GNUTLS_LIBRARY_LOG_LEVEL >= 0
294 static void exim_gnutls_logger_cb(int level, const char *message);
297 static int exim_sni_handling_cb(gnutls_session_t session);
299 #if !defined(DISABLE_OCSP)
300 static int server_ocsp_stapling_cb(gnutls_session_t session, void * ptr,
301 gnutls_datum_t * ocsp_response);
304 #ifdef EXPERIMENTAL_TLS_RESUME
306 tls_server_ticket_cb(gnutls_session_t sess, u_int htype, unsigned when,
307 unsigned incoming, const gnutls_datum_t * msg);
311 /* Daemon one-time initialisation */
313 tls_daemon_init(void)
315 #ifdef EXPERIMENTAL_TLS_RESUME
316 /* We are dependent on the GnuTLS implementation of the Session Ticket
317 encryption; both the strength and the key rotation period. We hope that
318 the strength at least matches that of the ciphersuite (but GnuTLS does not
321 static BOOL once = FALSE;
324 gnutls_session_ticket_key_generate(&server_sessticket_key); /* >= 2.10.0 */
325 if (f.running_in_test_harness) ssl_session_timeout = 6;
329 /* ------------------------------------------------------------------------ */
330 /* Static functions */
332 /*************************************************
334 *************************************************/
336 /* Called from lots of places when errors occur before actually starting to do
337 the TLS handshake, that is, while the session is still in clear. Always returns
338 DEFER for a server and FAIL for a client so that most calls can use "return
339 tls_error(...)" to do this processing and then give an appropriate return. A
340 single function is used for both server and client, because it is called from
341 some shared functions.
344 prefix text to include in the logged error
345 msg additional error string (may be NULL)
346 usually obtained from gnutls_strerror()
347 host NULL if setting up a server;
348 the connected host if setting up a client
349 errstr pointer to returned error string
351 Returns: OK/DEFER/FAIL
355 tls_error(const uschar *prefix, const uschar *msg, const host_item *host,
359 *errstr = string_sprintf("(%s)%s%s", prefix, msg ? ": " : "", msg ? msg : US"");
360 return host ? FAIL : DEFER;
365 tls_error_gnu(const uschar *prefix, int err, const host_item *host,
368 return tls_error(prefix, US gnutls_strerror(err), host, errstr);
372 tls_error_sys(const uschar *prefix, int err, const host_item *host,
375 return tls_error(prefix, US strerror(err), host, errstr);
379 /*************************************************
380 * Deal with logging errors during I/O *
381 *************************************************/
383 /* We have to get the identity of the peer from saved data.
386 state the current GnuTLS exim state container
387 rc the GnuTLS error code, or 0 if it's a local error
388 when text identifying read or write
389 text local error text when rc is 0
395 record_io_error(exim_gnutls_state_st *state, int rc, uschar *when, uschar *text)
400 if (rc == GNUTLS_E_FATAL_ALERT_RECEIVED)
401 msg = string_sprintf("A TLS fatal alert has been received: %s",
402 US gnutls_alert_get_name(gnutls_alert_get(state->session)));
404 msg = US gnutls_strerror(rc);
406 (void) tls_error(when, msg, state->host, &errstr);
409 log_write(0, LOG_MAIN, "H=%s [%s] TLS error on connection %s",
410 state->host->name, state->host->address, errstr);
413 uschar * conn_info = smtp_get_connection_info();
414 if (Ustrncmp(conn_info, US"SMTP ", 5) == 0) conn_info += 5;
415 /* I'd like to get separated H= here, but too hard for now */
416 log_write(0, LOG_MAIN, "TLS error on %s %s", conn_info, errstr);
423 /*************************************************
424 * Set various Exim expansion vars *
425 *************************************************/
427 #define exim_gnutls_cert_err(Label) \
430 if (rc != GNUTLS_E_SUCCESS) \
432 DEBUG(D_tls) debug_printf("TLS: cert problem: %s: %s\n", \
433 (Label), gnutls_strerror(rc)); \
439 import_cert(const gnutls_datum_t * cert, gnutls_x509_crt_t * crtp)
443 rc = gnutls_x509_crt_init(crtp);
444 exim_gnutls_cert_err(US"gnutls_x509_crt_init (crt)");
446 rc = gnutls_x509_crt_import(*crtp, cert, GNUTLS_X509_FMT_DER);
447 exim_gnutls_cert_err(US"failed to import certificate [gnutls_x509_crt_import(cert)]");
452 #undef exim_gnutls_cert_err
455 /* We set various Exim global variables from the state, once a session has
456 been established. With TLS callouts, may need to change this to stack
457 variables, or just re-call it with the server state after client callout
460 Make sure anything set here is unset in tls_getc().
464 tls_bits strength indicator
465 tls_certificate_verified bool indicator
466 tls_channelbinding_b64 for some SASL mechanisms
468 tls_peercert pointer to library internal
470 tls_sni a (UTF-8) string
471 tls_ourcert pointer to library internal
474 state the relevant exim_gnutls_state_st *
478 extract_exim_vars_from_tls_state(exim_gnutls_state_st * state)
480 #ifdef HAVE_GNUTLS_SESSION_CHANNEL_BINDING
483 gnutls_datum_t channel;
485 tls_support * tlsp = state->tlsp;
487 tlsp->active.sock = state->fd_out;
488 tlsp->active.tls_ctx = state;
490 DEBUG(D_tls) debug_printf("cipher: %s\n", state->ciphersuite);
492 tlsp->certificate_verified = state->peer_cert_verified;
494 tlsp->dane_verified = state->peer_dane_verified;
497 /* note that tls_channelbinding_b64 is not saved to the spool file, since it's
498 only available for use for authenticators while this TLS session is running. */
500 tls_channelbinding_b64 = NULL;
501 #ifdef HAVE_GNUTLS_SESSION_CHANNEL_BINDING
504 if ((rc = gnutls_session_channel_binding(state->session, GNUTLS_CB_TLS_UNIQUE, &channel)))
505 { DEBUG(D_tls) debug_printf("Channel binding error: %s\n", gnutls_strerror(rc)); }
508 old_pool = store_pool;
509 store_pool = POOL_PERM;
510 tls_channelbinding_b64 = b64encode(CUS channel.data, (int)channel.size);
511 store_pool = old_pool;
512 DEBUG(D_tls) debug_printf("Have channel bindings cached for possible auth usage.\n");
516 /* peercert is set in peer_status() */
517 tlsp->peerdn = state->peerdn;
518 tlsp->sni = state->received_sni;
520 /* record our certificate */
522 const gnutls_datum_t * cert = gnutls_certificate_get_ours(state->session);
523 gnutls_x509_crt_t crt;
525 tlsp->ourcert = cert && import_cert(cert, &crt)==0 ? crt : NULL;
532 /*************************************************
533 * Setup up DH parameters *
534 *************************************************/
536 /* Generating the D-H parameters may take a long time. They only need to
537 be re-generated every so often, depending on security policy. What we do is to
538 keep these parameters in a file in the spool directory. If the file does not
539 exist, we generate them. This means that it is easy to cause a regeneration.
541 The new file is written as a temporary file and renamed, so that an incomplete
542 file is never present. If two processes both compute some new parameters, you
543 waste a bit of effort, but it doesn't seem worth messing around with locking to
546 Returns: OK/DEFER/FAIL
550 init_server_dh(uschar ** errstr)
553 unsigned int dh_bits;
555 uschar filename_buf[PATH_MAX];
556 uschar *filename = NULL;
558 uschar *exp_tls_dhparam;
559 BOOL use_file_in_spool = FALSE;
560 host_item *host = NULL; /* dummy for macros */
562 DEBUG(D_tls) debug_printf("Initialising GnuTLS server params.\n");
564 if ((rc = gnutls_dh_params_init(&dh_server_params)))
565 return tls_error_gnu(US"gnutls_dh_params_init", rc, host, errstr);
570 if (!expand_check(tls_dhparam, US"tls_dhparam", &exp_tls_dhparam, errstr))
573 if (!exp_tls_dhparam)
575 DEBUG(D_tls) debug_printf("Loading default hard-coded DH params\n");
576 m.data = US std_dh_prime_default();
577 m.size = Ustrlen(m.data);
579 else if (Ustrcmp(exp_tls_dhparam, "historic") == 0)
580 use_file_in_spool = TRUE;
581 else if (Ustrcmp(exp_tls_dhparam, "none") == 0)
583 DEBUG(D_tls) debug_printf("Requested no DH parameters.\n");
586 else if (exp_tls_dhparam[0] != '/')
588 if (!(m.data = US std_dh_prime_named(exp_tls_dhparam)))
589 return tls_error(US"No standard prime named", exp_tls_dhparam, NULL, errstr);
590 m.size = Ustrlen(m.data);
593 filename = exp_tls_dhparam;
597 if ((rc = gnutls_dh_params_import_pkcs3(dh_server_params, &m, GNUTLS_X509_FMT_PEM)))
598 return tls_error_gnu(US"gnutls_dh_params_import_pkcs3", rc, host, errstr);
599 DEBUG(D_tls) debug_printf("Loaded fixed standard D-H parameters\n");
603 #ifdef HAVE_GNUTLS_SEC_PARAM_CONSTANTS
604 /* If you change this constant, also change dh_param_fn_ext so that we can use a
605 different filename and ensure we have sufficient bits. */
607 if (!(dh_bits = gnutls_sec_param_to_pk_bits(GNUTLS_PK_DH, GNUTLS_SEC_PARAM_NORMAL)))
608 return tls_error(US"gnutls_sec_param_to_pk_bits() failed", NULL, NULL, errstr);
610 debug_printf("GnuTLS tells us that for D-H PK, NORMAL is %d bits.\n",
613 dh_bits = EXIM_SERVER_DH_BITS_PRE2_12;
615 debug_printf("GnuTLS lacks gnutls_sec_param_to_pk_bits(), using %d bits.\n",
619 /* Some clients have hard-coded limits. */
620 if (dh_bits > tls_dh_max_bits)
623 debug_printf("tls_dh_max_bits clamping override, using %d bits instead.\n",
625 dh_bits = tls_dh_max_bits;
628 if (use_file_in_spool)
630 if (!string_format(filename_buf, sizeof(filename_buf),
631 "%s/gnutls-params-%d", spool_directory, dh_bits))
632 return tls_error(US"overlong filename", NULL, NULL, errstr);
633 filename = filename_buf;
636 /* Open the cache file for reading and if successful, read it and set up the
639 if ((fd = Uopen(filename, O_RDONLY, 0)) >= 0)
645 if (fstat(fd, &statbuf) < 0) /* EIO */
649 return tls_error_sys(US"TLS cache stat failed", saved_errno, NULL, errstr);
651 if (!S_ISREG(statbuf.st_mode))
654 return tls_error(US"TLS cache not a file", NULL, NULL, errstr);
656 if (!(fp = fdopen(fd, "rb")))
660 return tls_error_sys(US"fdopen(TLS cache stat fd) failed",
661 saved_errno, NULL, errstr);
664 m.size = statbuf.st_size;
665 if (!(m.data = store_malloc(m.size)))
668 return tls_error_sys(US"malloc failed", errno, NULL, errstr);
670 if (!(sz = fread(m.data, m.size, 1, fp)))
675 return tls_error_sys(US"fread failed", saved_errno, NULL, errstr);
679 rc = gnutls_dh_params_import_pkcs3(dh_server_params, &m, GNUTLS_X509_FMT_PEM);
682 return tls_error_gnu(US"gnutls_dh_params_import_pkcs3", rc, host, errstr);
683 DEBUG(D_tls) debug_printf("read D-H parameters from file \"%s\"\n", filename);
686 /* If the file does not exist, fall through to compute new data and cache it.
687 If there was any other opening error, it is serious. */
689 else if (errno == ENOENT)
693 debug_printf("D-H parameter cache file \"%s\" does not exist\n", filename);
696 return tls_error(string_open_failed(errno, "\"%s\" for reading", filename),
699 /* If ret < 0, either the cache file does not exist, or the data it contains
700 is not useful. One particular case of this is when upgrading from an older
701 release of Exim in which the data was stored in a different format. We don't
702 try to be clever and support both formats; we just regenerate new data in this
708 unsigned int dh_bits_gen = dh_bits;
710 if ((PATH_MAX - Ustrlen(filename)) < 10)
711 return tls_error(US"Filename too long to generate replacement",
712 filename, NULL, errstr);
714 temp_fn = string_copy(US"%s.XXXXXXX");
715 if ((fd = mkstemp(CS temp_fn)) < 0) /* modifies temp_fn */
716 return tls_error_sys(US"Unable to open temp file", errno, NULL, errstr);
717 (void)exim_chown(temp_fn, exim_uid, exim_gid); /* Probably not necessary */
719 /* GnuTLS overshoots!
720 * If we ask for 2236, we might get 2237 or more.
721 * But there's no way to ask GnuTLS how many bits there really are.
722 * We can ask how many bits were used in a TLS session, but that's it!
723 * The prime itself is hidden behind too much abstraction.
724 * So we ask for less, and proceed on a wing and a prayer.
725 * First attempt, subtracted 3 for 2233 and got 2240.
727 if (dh_bits >= EXIM_CLIENT_DH_MIN_BITS + 10)
729 dh_bits_gen = dh_bits - 10;
731 debug_printf("being paranoid about DH generation, make it '%d' bits'\n",
736 debug_printf("requesting generation of %d bit Diffie-Hellman prime ...\n",
738 if ((rc = gnutls_dh_params_generate2(dh_server_params, dh_bits_gen)))
739 return tls_error_gnu(US"gnutls_dh_params_generate2", rc, host, errstr);
741 /* gnutls_dh_params_export_pkcs3() will tell us the exact size, every time,
742 and I confirmed that a NULL call to get the size first is how the GnuTLS
743 sample apps handle this. */
747 if ( (rc = gnutls_dh_params_export_pkcs3(dh_server_params,
748 GNUTLS_X509_FMT_PEM, m.data, &sz))
749 && rc != GNUTLS_E_SHORT_MEMORY_BUFFER)
750 return tls_error_gnu(US"gnutls_dh_params_export_pkcs3(NULL) sizing",
753 if (!(m.data = store_malloc(m.size)))
754 return tls_error_sys(US"memory allocation failed", errno, NULL, errstr);
756 /* this will return a size 1 less than the allocation size above */
757 if ((rc = gnutls_dh_params_export_pkcs3(dh_server_params, GNUTLS_X509_FMT_PEM,
761 return tls_error_gnu(US"gnutls_dh_params_export_pkcs3() real", rc, host, errstr);
763 m.size = sz; /* shrink by 1, probably */
765 if ((sz = write_to_fd_buf(fd, m.data, (size_t) m.size)) != m.size)
768 return tls_error_sys(US"TLS cache write D-H params failed",
769 errno, NULL, errstr);
772 if ((sz = write_to_fd_buf(fd, US"\n", 1)) != 1)
773 return tls_error_sys(US"TLS cache write D-H params final newline failed",
774 errno, NULL, errstr);
776 if ((rc = close(fd)))
777 return tls_error_sys(US"TLS cache write close() failed", errno, NULL, errstr);
779 if (Urename(temp_fn, filename) < 0)
780 return tls_error_sys(string_sprintf("failed to rename \"%s\" as \"%s\"",
781 temp_fn, filename), errno, NULL, errstr);
783 DEBUG(D_tls) debug_printf("wrote D-H parameters to file \"%s\"\n", filename);
786 DEBUG(D_tls) debug_printf("initialized server D-H parameters\n");
793 /* Create and install a selfsigned certificate, for use in server mode */
796 tls_install_selfsign(exim_gnutls_state_st * state, uschar ** errstr)
798 gnutls_x509_crt_t cert = NULL;
800 gnutls_x509_privkey_t pkey = NULL;
801 const uschar * where;
804 where = US"initialising pkey";
805 if ((rc = gnutls_x509_privkey_init(&pkey))) goto err;
807 where = US"initialising cert";
808 if ((rc = gnutls_x509_crt_init(&cert))) goto err;
810 where = US"generating pkey";
811 if ((rc = gnutls_x509_privkey_generate(pkey, GNUTLS_PK_RSA,
812 #ifdef SUPPORT_PARAM_TO_PK_BITS
813 # ifndef GNUTLS_SEC_PARAM_MEDIUM
814 # define GNUTLS_SEC_PARAM_MEDIUM GNUTLS_SEC_PARAM_HIGH
816 gnutls_sec_param_to_pk_bits(GNUTLS_PK_RSA, GNUTLS_SEC_PARAM_MEDIUM),
823 where = US"configuring cert";
825 if ( (rc = gnutls_x509_crt_set_version(cert, 3))
826 || (rc = gnutls_x509_crt_set_serial(cert, &now, sizeof(now)))
827 || (rc = gnutls_x509_crt_set_activation_time(cert, now = time(NULL)))
828 || (rc = gnutls_x509_crt_set_expiration_time(cert, now + 60 * 60)) /* 1 hr */
829 || (rc = gnutls_x509_crt_set_key(cert, pkey))
831 || (rc = gnutls_x509_crt_set_dn_by_oid(cert,
832 GNUTLS_OID_X520_COUNTRY_NAME, 0, "UK", 2))
833 || (rc = gnutls_x509_crt_set_dn_by_oid(cert,
834 GNUTLS_OID_X520_ORGANIZATION_NAME, 0, "Exim Developers", 15))
835 || (rc = gnutls_x509_crt_set_dn_by_oid(cert,
836 GNUTLS_OID_X520_COMMON_NAME, 0,
837 smtp_active_hostname, Ustrlen(smtp_active_hostname)))
841 where = US"signing cert";
842 if ((rc = gnutls_x509_crt_sign(cert, cert, pkey))) goto err;
844 where = US"installing selfsign cert";
846 if ((rc = gnutls_certificate_set_x509_key(state->x509_cred, &cert, 1, pkey)))
852 if (cert) gnutls_x509_crt_deinit(cert);
853 if (pkey) gnutls_x509_privkey_deinit(pkey);
857 rc = tls_error_gnu(where, rc, NULL, errstr);
864 /* Add certificate and key, from files.
867 Zero or negative: good. Negate value for certificate index if < 0.
868 Greater than zero: FAIL or DEFER code.
872 tls_add_certfile(exim_gnutls_state_st * state, const host_item * host,
873 uschar * certfile, uschar * keyfile, uschar ** errstr)
875 int rc = gnutls_certificate_set_x509_key_file(state->x509_cred,
876 CS certfile, CS keyfile, GNUTLS_X509_FMT_PEM);
878 return tls_error_gnu(
879 string_sprintf("cert/key setup: cert=%s key=%s", certfile, keyfile),
885 #ifdef SUPPORT_GNUTLS_EXT_RAW_PARSE
886 /* Make a note that we saw a status-request */
888 tls_server_clienthello_ext(void * ctx, unsigned tls_id,
889 const unsigned char *data, unsigned size)
891 /* https://www.iana.org/assignments/tls-extensiontype-values/tls-extensiontype-values.xhtml */
892 if (tls_id == 5) /* status_request */
894 DEBUG(D_tls) debug_printf("Seen status_request extension from client\n");
895 tls_in.ocsp = OCSP_NOT_RESP;
900 /* Callback for client-hello, on server, if we think we might serve stapled-OCSP */
902 tls_server_clienthello_cb(gnutls_session_t session, unsigned int htype,
903 unsigned when, unsigned int incoming, const gnutls_datum_t * msg)
905 /* Call fn for each extension seen. 3.6.3 onwards */
906 return gnutls_ext_raw_parse(NULL, tls_server_clienthello_ext, msg,
907 GNUTLS_EXT_RAW_FLAG_TLS_CLIENT_HELLO);
911 /* Make a note that we saw a status-response */
913 tls_server_servercerts_ext(void * ctx, unsigned tls_id,
914 const unsigned char *data, unsigned size)
916 /* debug_printf("%s %u\n", __FUNCTION__, tls_id); */
917 /* https://www.iana.org/assignments/tls-extensiontype-values/tls-extensiontype-values.xhtml */
918 if (FALSE && tls_id == 5) /* status_request */
920 DEBUG(D_tls) debug_printf("Seen status_request extension\n");
921 tls_in.ocsp = exim_testharness_disable_ocsp_validity_check
922 ? OCSP_VFY_NOT_TRIED : OCSP_VFIED; /* We know that GnuTLS verifies responses */
927 /* Callback for certificates packet, on server, if we think we might serve stapled-OCSP */
929 tls_server_servercerts_cb(gnutls_session_t session, unsigned int htype,
930 unsigned when, unsigned int incoming, const gnutls_datum_t * msg)
932 /* Call fn for each extension seen. 3.6.3 onwards */
935 return gnutls_ext_raw_parse(NULL, tls_server_servercerts_ext, msg, 0);
940 /*XXX in tls1.3 the cert-status travel as an extension next to the cert, in the
941 "Handshake Protocol: Certificate" record.
942 So we need to spot the Certificate handshake message, parse it and spot any status_request extension(s)
944 This is different to tls1.2 - where it is a separate record (wireshake term) / handshake message (gnutls term).
947 #if defined(EXPERIMENTAL_TLS_RESUME) || defined(SUPPORT_GNUTLS_EXT_RAW_PARSE)
948 /* Callback for certificate-status, on server. We sent stapled OCSP. */
950 tls_server_certstatus_cb(gnutls_session_t session, unsigned int htype,
951 unsigned when, unsigned int incoming, const gnutls_datum_t * msg)
953 DEBUG(D_tls) debug_printf("Sending certificate-status\n"); /*XXX we get this for tls1.2 but not for 1.3 */
954 #ifdef SUPPORT_SRV_OCSP_STACK
955 tls_in.ocsp = exim_testharness_disable_ocsp_validity_check
956 ? OCSP_VFY_NOT_TRIED : OCSP_VFIED; /* We know that GnuTLS verifies responses */
958 tls_in.ocsp = OCSP_VFY_NOT_TRIED;
963 /* Callback for handshake messages, on server */
965 tls_server_hook_cb(gnutls_session_t sess, u_int htype, unsigned when,
966 unsigned incoming, const gnutls_datum_t * msg)
968 /* debug_printf("%s: htype %u\n", __FUNCTION__, htype); */
971 # ifdef SUPPORT_GNUTLS_EXT_RAW_PARSE
972 case GNUTLS_HANDSHAKE_CLIENT_HELLO:
973 return tls_server_clienthello_cb(sess, htype, when, incoming, msg);
974 case GNUTLS_HANDSHAKE_CERTIFICATE_PKT:
975 return tls_server_servercerts_cb(sess, htype, when, incoming, msg);
977 case GNUTLS_HANDSHAKE_CERTIFICATE_STATUS:
978 return tls_server_certstatus_cb(sess, htype, when, incoming, msg);
979 # ifdef EXPERIMENTAL_TLS_RESUME
980 case GNUTLS_HANDSHAKE_NEW_SESSION_TICKET:
981 return tls_server_ticket_cb(sess, htype, when, incoming, msg);
990 #if !defined(DISABLE_OCSP) && defined(SUPPORT_GNUTLS_EXT_RAW_PARSE)
992 tls_server_testharness_ocsp_fiddle(void)
994 extern char ** environ;
995 if (environ) for (uschar ** p = USS environ; *p; p++)
996 if (Ustrncmp(*p, "EXIM_TESTHARNESS_DISABLE_OCSPVALIDITYCHECK", 42) == 0)
998 DEBUG(D_tls) debug_printf("Permitting known bad OCSP response\n");
999 exim_testharness_disable_ocsp_validity_check = TRUE;
1004 /*************************************************
1005 * Variables re-expanded post-SNI *
1006 *************************************************/
1008 /* Called from both server and client code, via tls_init(), and also from
1009 the SNI callback after receiving an SNI, if tls_certificate includes "tls_sni".
1011 We can tell the two apart by state->received_sni being non-NULL in callback.
1013 The callback should not call us unless state->trigger_sni_changes is true,
1014 which we are responsible for setting on the first pass through.
1017 state exim_gnutls_state_st *
1018 errstr error string pointer
1020 Returns: OK/DEFER/FAIL
1024 tls_expand_session_files(exim_gnutls_state_st * state, uschar ** errstr)
1026 struct stat statbuf;
1028 const host_item *host = state->host; /* macro should be reconsidered? */
1029 uschar *saved_tls_certificate = NULL;
1030 uschar *saved_tls_privatekey = NULL;
1031 uschar *saved_tls_verify_certificates = NULL;
1032 uschar *saved_tls_crl = NULL;
1035 /* We check for tls_sni *before* expansion. */
1036 if (!host) /* server */
1037 if (!state->received_sni)
1039 if ( state->tls_certificate
1040 && ( Ustrstr(state->tls_certificate, US"tls_sni")
1041 || Ustrstr(state->tls_certificate, US"tls_in_sni")
1042 || Ustrstr(state->tls_certificate, US"tls_out_sni")
1045 DEBUG(D_tls) debug_printf("We will re-expand TLS session files if we receive SNI.\n");
1046 state->trigger_sni_changes = TRUE;
1051 /* useful for debugging */
1052 saved_tls_certificate = state->exp_tls_certificate;
1053 saved_tls_privatekey = state->exp_tls_privatekey;
1054 saved_tls_verify_certificates = state->exp_tls_verify_certificates;
1055 saved_tls_crl = state->exp_tls_crl;
1058 if ((rc = gnutls_certificate_allocate_credentials(&state->x509_cred)))
1059 return tls_error_gnu(US"gnutls_certificate_allocate_credentials",
1062 #ifdef SUPPORT_SRV_OCSP_STACK
1063 gnutls_certificate_set_flags(state->x509_cred, GNUTLS_CERTIFICATE_API_V2);
1065 # if !defined(DISABLE_OCSP) && defined(SUPPORT_GNUTLS_EXT_RAW_PARSE)
1066 if (!host && tls_ocsp_file)
1068 if (f.running_in_test_harness)
1069 tls_server_testharness_ocsp_fiddle();
1071 if (exim_testharness_disable_ocsp_validity_check)
1072 gnutls_certificate_set_flags(state->x509_cred,
1073 GNUTLS_CERTIFICATE_API_V2 | GNUTLS_CERTIFICATE_SKIP_OCSP_RESPONSE_CHECK);
1078 /* remember: expand_check_tlsvar() is expand_check() but fiddling with
1079 state members, assuming consistent naming; and expand_check() returns
1080 false if expansion failed, unless expansion was forced to fail. */
1082 /* check if we at least have a certificate, before doing expensive
1085 if (!expand_check_tlsvar(tls_certificate, errstr))
1088 /* certificate is mandatory in server, optional in client */
1090 if ( !state->exp_tls_certificate
1091 || !*state->exp_tls_certificate
1094 return tls_install_selfsign(state, errstr);
1096 DEBUG(D_tls) debug_printf("TLS: no client certificate specified; okay\n");
1098 if (state->tls_privatekey && !expand_check_tlsvar(tls_privatekey, errstr))
1101 /* tls_privatekey is optional, defaulting to same file as certificate */
1103 if (!state->tls_privatekey || !*state->tls_privatekey)
1105 state->tls_privatekey = state->tls_certificate;
1106 state->exp_tls_privatekey = state->exp_tls_certificate;
1110 if (state->exp_tls_certificate && *state->exp_tls_certificate)
1112 DEBUG(D_tls) debug_printf("certificate file = %s\nkey file = %s\n",
1113 state->exp_tls_certificate, state->exp_tls_privatekey);
1115 if (state->received_sni)
1116 if ( Ustrcmp(state->exp_tls_certificate, saved_tls_certificate) == 0
1117 && Ustrcmp(state->exp_tls_privatekey, saved_tls_privatekey) == 0
1120 DEBUG(D_tls) debug_printf("TLS SNI: cert and key unchanged\n");
1124 DEBUG(D_tls) debug_printf("TLS SNI: have a changed cert/key pair.\n");
1127 if (!host) /* server */
1129 const uschar * clist = state->exp_tls_certificate;
1130 const uschar * klist = state->exp_tls_privatekey;
1131 const uschar * olist;
1132 int csep = 0, ksep = 0, osep = 0, cnt = 0;
1133 uschar * cfile, * kfile, * ofile;
1134 #ifndef DISABLE_OCSP
1135 # ifdef SUPPORT_GNUTLS_EXT_RAW_PARSE
1136 gnutls_x509_crt_fmt_t ocsp_fmt = GNUTLS_X509_FMT_DER;
1139 if (!expand_check(tls_ocsp_file, US"tls_ocsp_file", &ofile, errstr))
1144 while (cfile = string_nextinlist(&clist, &csep, NULL, 0))
1146 if (!(kfile = string_nextinlist(&klist, &ksep, NULL, 0)))
1147 return tls_error(US"cert/key setup: out of keys", NULL, host, errstr);
1148 else if (0 < (rc = tls_add_certfile(state, host, cfile, kfile, errstr)))
1152 int gnutls_cert_index = -rc;
1153 DEBUG(D_tls) debug_printf("TLS: cert/key %d %s registered\n",
1154 gnutls_cert_index, cfile);
1156 #ifndef DISABLE_OCSP
1159 /* Set the OCSP stapling server info */
1160 if (gnutls_buggy_ocsp)
1163 debug_printf("GnuTLS library is buggy for OCSP; avoiding\n");
1165 else if ((ofile = string_nextinlist(&olist, &osep, NULL, 0)))
1167 DEBUG(D_tls) debug_printf("OCSP response file %d = %s\n",
1168 gnutls_cert_index, ofile);
1169 # ifdef SUPPORT_GNUTLS_EXT_RAW_PARSE
1170 if (Ustrncmp(ofile, US"PEM ", 4) == 0)
1172 ocsp_fmt = GNUTLS_X509_FMT_PEM;
1175 else if (Ustrncmp(ofile, US"DER ", 4) == 0)
1177 ocsp_fmt = GNUTLS_X509_FMT_DER;
1181 if ((rc = gnutls_certificate_set_ocsp_status_request_file2(
1182 state->x509_cred, CCS ofile, gnutls_cert_index,
1184 return tls_error_gnu(
1185 US"gnutls_certificate_set_ocsp_status_request_file2",
1188 debug_printf(" %d response%s loaded\n", rc, rc>1 ? "s":"");
1190 /* Arrange callbacks for OCSP request observability */
1192 gnutls_handshake_set_hook_function(state->session,
1193 GNUTLS_HANDSHAKE_ANY, GNUTLS_HOOK_POST, tls_server_hook_cb);
1196 # if defined(SUPPORT_SRV_OCSP_STACK)
1197 if ((rc = gnutls_certificate_set_ocsp_status_request_function2(
1198 state->x509_cred, gnutls_cert_index,
1199 server_ocsp_stapling_cb, ofile)))
1200 return tls_error_gnu(
1201 US"gnutls_certificate_set_ocsp_status_request_function2",
1209 debug_printf("oops; multiple OCSP files not supported\n");
1212 gnutls_certificate_set_ocsp_status_request_function(
1213 state->x509_cred, server_ocsp_stapling_cb, ofile);
1215 # endif /* SUPPORT_GNUTLS_EXT_RAW_PARSE */
1218 DEBUG(D_tls) debug_printf("ran out of OCSP response files in list\n");
1220 #endif /* DISABLE_OCSP */
1225 if (0 < (rc = tls_add_certfile(state, host,
1226 state->exp_tls_certificate, state->exp_tls_privatekey, errstr)))
1228 DEBUG(D_tls) debug_printf("TLS: cert/key registered\n");
1231 } /* tls_certificate */
1234 /* Set the trusted CAs file if one is provided, and then add the CRL if one is
1235 provided. Experiment shows that, if the certificate file is empty, an unhelpful
1236 error message is provided. However, if we just refrain from setting anything up
1237 in that case, certificate verification fails, which seems to be the correct
1240 if (state->tls_verify_certificates && *state->tls_verify_certificates)
1242 if (!expand_check_tlsvar(tls_verify_certificates, errstr))
1244 #ifndef SUPPORT_SYSDEFAULT_CABUNDLE
1245 if (Ustrcmp(state->exp_tls_verify_certificates, "system") == 0)
1246 state->exp_tls_verify_certificates = NULL;
1248 if (state->tls_crl && *state->tls_crl)
1249 if (!expand_check_tlsvar(tls_crl, errstr))
1252 if (!(state->exp_tls_verify_certificates &&
1253 *state->exp_tls_verify_certificates))
1256 debug_printf("TLS: tls_verify_certificates expanded empty, ignoring\n");
1257 /* With no tls_verify_certificates, we ignore tls_crl too */
1264 debug_printf("TLS: tls_verify_certificates not set or empty, ignoring\n");
1268 #ifdef SUPPORT_SYSDEFAULT_CABUNDLE
1269 if (Ustrcmp(state->exp_tls_verify_certificates, "system") == 0)
1270 cert_count = gnutls_certificate_set_x509_system_trust(state->x509_cred);
1274 if (Ustat(state->exp_tls_verify_certificates, &statbuf) < 0)
1276 log_write(0, LOG_MAIN|LOG_PANIC, "could not stat %s "
1277 "(tls_verify_certificates): %s", state->exp_tls_verify_certificates,
1282 #ifndef SUPPORT_CA_DIR
1283 /* The test suite passes in /dev/null; we could check for that path explicitly,
1284 but who knows if someone has some weird FIFO which always dumps some certs, or
1285 other weirdness. The thing we really want to check is that it's not a
1286 directory, since while OpenSSL supports that, GnuTLS does not.
1287 So s/!S_ISREG/S_ISDIR/ and change some messaging ... */
1288 if (S_ISDIR(statbuf.st_mode))
1291 debug_printf("verify certificates path is a dir: \"%s\"\n",
1292 state->exp_tls_verify_certificates);
1293 log_write(0, LOG_MAIN|LOG_PANIC,
1294 "tls_verify_certificates \"%s\" is a directory",
1295 state->exp_tls_verify_certificates);
1300 DEBUG(D_tls) debug_printf("verify certificates = %s size=" OFF_T_FMT "\n",
1301 state->exp_tls_verify_certificates, statbuf.st_size);
1303 if (statbuf.st_size == 0)
1306 debug_printf("cert file empty, no certs, no verification, ignoring any CRL\n");
1312 #ifdef SUPPORT_CA_DIR
1313 (statbuf.st_mode & S_IFMT) == S_IFDIR
1315 gnutls_certificate_set_x509_trust_dir(state->x509_cred,
1316 CS state->exp_tls_verify_certificates, GNUTLS_X509_FMT_PEM)
1319 gnutls_certificate_set_x509_trust_file(state->x509_cred,
1320 CS state->exp_tls_verify_certificates, GNUTLS_X509_FMT_PEM);
1322 #ifdef SUPPORT_CA_DIR
1323 /* Mimic the behaviour with OpenSSL of not advertising a usable-cert list
1324 when using the directory-of-certs config model. */
1326 if ((statbuf.st_mode & S_IFMT) == S_IFDIR)
1327 gnutls_certificate_send_x509_rdn_sequence(state->session, 1);
1332 return tls_error_gnu(US"setting certificate trust", cert_count, host, errstr);
1334 debug_printf("Added %d certificate authorities.\n", cert_count);
1336 if (state->tls_crl && *state->tls_crl &&
1337 state->exp_tls_crl && *state->exp_tls_crl)
1339 DEBUG(D_tls) debug_printf("loading CRL file = %s\n", state->exp_tls_crl);
1340 if ((cert_count = gnutls_certificate_set_x509_crl_file(state->x509_cred,
1341 CS state->exp_tls_crl, GNUTLS_X509_FMT_PEM)) < 0)
1342 return tls_error_gnu(US"gnutls_certificate_set_x509_crl_file",
1343 cert_count, host, errstr);
1345 DEBUG(D_tls) debug_printf("Processed %d CRLs.\n", cert_count);
1354 /*************************************************
1355 * Set X.509 state variables *
1356 *************************************************/
1358 /* In GnuTLS, the registered cert/key are not replaced by a later
1359 set of a cert/key, so for SNI support we need a whole new x509_cred
1360 structure. Which means various other non-re-expanded pieces of state
1361 need to be re-set in the new struct, so the setting logic is pulled
1365 state exim_gnutls_state_st *
1366 errstr error string pointer
1368 Returns: OK/DEFER/FAIL
1372 tls_set_remaining_x509(exim_gnutls_state_st *state, uschar ** errstr)
1375 const host_item *host = state->host; /* macro should be reconsidered? */
1377 /* Create D-H parameters, or read them from the cache file. This function does
1378 its own SMTP error messaging. This only happens for the server, TLS D-H ignores
1379 client-side params. */
1383 if (!dh_server_params)
1384 if ((rc = init_server_dh(errstr)) != OK) return rc;
1385 gnutls_certificate_set_dh_params(state->x509_cred, dh_server_params);
1388 /* Link the credentials to the session. */
1390 if ((rc = gnutls_credentials_set(state->session,
1391 GNUTLS_CRD_CERTIFICATE, state->x509_cred)))
1392 return tls_error_gnu(US"gnutls_credentials_set", rc, host, errstr);
1397 /*************************************************
1398 * Initialize for GnuTLS *
1399 *************************************************/
1402 #ifndef DISABLE_OCSP
1405 tls_is_buggy_ocsp(void)
1408 uschar maj, mid, mic;
1410 s = CUS gnutls_check_version(NULL);
1414 while (*s && *s != '.') s++;
1415 mid = atoi(CCS ++s);
1422 while (*s && *s != '.') s++;
1423 mic = atoi(CCS ++s);
1424 return mic <= (mid == 3 ? 16 : 3);
1433 /* Called from both server and client code. In the case of a server, errors
1434 before actual TLS negotiation return DEFER.
1437 host connected host, if client; NULL if server
1438 certificate certificate file
1439 privatekey private key file
1440 sni TLS SNI to send, sometimes when client; else NULL
1443 require_ciphers tls_require_ciphers setting
1444 caller_state returned state-info structure
1445 errstr error string pointer
1447 Returns: OK/DEFER/FAIL
1452 const host_item *host,
1453 const uschar *certificate,
1454 const uschar *privatekey,
1458 const uschar *require_ciphers,
1459 exim_gnutls_state_st **caller_state,
1463 exim_gnutls_state_st * state;
1466 const char * errpos;
1469 if (!exim_gnutls_base_init_done)
1471 DEBUG(D_tls) debug_printf("GnuTLS global init required.\n");
1473 #ifdef HAVE_GNUTLS_PKCS11
1474 /* By default, gnutls_global_init will init PKCS11 support in auto mode,
1475 which loads modules from a config file, which sounds good and may be wanted
1476 by some sysadmin, but also means in common configurations that GNOME keyring
1477 environment variables are used and so breaks for users calling mailq.
1478 To prevent this, we init PKCS11 first, which is the documented approach. */
1479 if (!gnutls_allow_auto_pkcs11)
1480 if ((rc = gnutls_pkcs11_init(GNUTLS_PKCS11_FLAG_MANUAL, NULL)))
1481 return tls_error_gnu(US"gnutls_pkcs11_init", rc, host, errstr);
1484 if ((rc = gnutls_global_init()))
1485 return tls_error_gnu(US"gnutls_global_init", rc, host, errstr);
1487 #if EXIM_GNUTLS_LIBRARY_LOG_LEVEL >= 0
1490 gnutls_global_set_log_function(exim_gnutls_logger_cb);
1491 /* arbitrarily chosen level; bump up to 9 for more */
1492 gnutls_global_set_log_level(EXIM_GNUTLS_LIBRARY_LOG_LEVEL);
1496 #ifndef DISABLE_OCSP
1497 if (tls_ocsp_file && (gnutls_buggy_ocsp = tls_is_buggy_ocsp()))
1498 log_write(0, LOG_MAIN, "OCSP unusable with this GnuTLS library version");
1501 exim_gnutls_base_init_done = TRUE;
1506 /* For client-side sessions we allocate a context. This lets us run
1507 several in parallel. */
1508 int old_pool = store_pool;
1509 store_pool = POOL_PERM;
1510 state = store_get(sizeof(exim_gnutls_state_st), FALSE);
1511 store_pool = old_pool;
1513 memcpy(state, &exim_gnutls_state_init, sizeof(exim_gnutls_state_init));
1515 DEBUG(D_tls) debug_printf("initialising GnuTLS client session\n");
1516 rc = gnutls_init(&state->session, GNUTLS_CLIENT);
1520 state = &state_server;
1521 memcpy(state, &exim_gnutls_state_init, sizeof(exim_gnutls_state_init));
1523 DEBUG(D_tls) debug_printf("initialising GnuTLS server session\n");
1524 rc = gnutls_init(&state->session, GNUTLS_SERVER);
1527 return tls_error_gnu(US"gnutls_init", rc, host, errstr);
1531 state->tls_certificate = certificate;
1532 state->tls_privatekey = privatekey;
1533 state->tls_require_ciphers = require_ciphers;
1534 state->tls_sni = sni;
1535 state->tls_verify_certificates = cas;
1536 state->tls_crl = crl;
1538 /* This handles the variables that might get re-expanded after TLS SNI;
1539 that's tls_certificate, tls_privatekey, tls_verify_certificates, tls_crl */
1542 debug_printf("Expanding various TLS configuration options for session credentials.\n");
1543 if ((rc = tls_expand_session_files(state, errstr)) != OK) return rc;
1545 /* These are all other parts of the x509_cred handling, since SNI in GnuTLS
1546 requires a new structure afterwards. */
1548 if ((rc = tls_set_remaining_x509(state, errstr)) != OK) return rc;
1550 /* set SNI in client, only */
1553 if (!expand_check(sni, US"tls_out_sni", &state->tlsp->sni, errstr))
1555 if (state->tlsp->sni && *state->tlsp->sni)
1558 debug_printf("Setting TLS client SNI to \"%s\"\n", state->tlsp->sni);
1559 sz = Ustrlen(state->tlsp->sni);
1560 if ((rc = gnutls_server_name_set(state->session,
1561 GNUTLS_NAME_DNS, state->tlsp->sni, sz)))
1562 return tls_error_gnu(US"gnutls_server_name_set", rc, host, errstr);
1565 else if (state->tls_sni)
1566 DEBUG(D_tls) debug_printf("*** PROBABLY A BUG *** " \
1567 "have an SNI set for a server [%s]\n", state->tls_sni);
1569 /* This is the priority string support,
1570 http://www.gnutls.org/manual/html_node/Priority-Strings.html
1571 and replaces gnutls_require_kx, gnutls_require_mac & gnutls_require_protocols.
1572 This was backwards incompatible, but means Exim no longer needs to track
1573 all algorithms and provide string forms for them. */
1576 if (state->tls_require_ciphers && *state->tls_require_ciphers)
1578 if (!expand_check_tlsvar(tls_require_ciphers, errstr))
1580 if (state->exp_tls_require_ciphers && *state->exp_tls_require_ciphers)
1582 p = state->exp_tls_require_ciphers;
1583 DEBUG(D_tls) debug_printf("GnuTLS session cipher/priority \"%s\"\n", p);
1588 p = exim_default_gnutls_priority;
1590 debug_printf("GnuTLS using default session cipher/priority \"%s\"\n", p);
1593 if ((rc = gnutls_priority_init(&state->priority_cache, CCS p, &errpos)))
1594 return tls_error_gnu(string_sprintf(
1595 "gnutls_priority_init(%s) failed at offset %ld, \"%.6s..\"",
1596 p, errpos - CS p, errpos),
1599 if ((rc = gnutls_priority_set(state->session, state->priority_cache)))
1600 return tls_error_gnu(US"gnutls_priority_set", rc, host, errstr);
1602 /* This also sets the server ticket expiration time to the same, and
1603 the STEK rotation time to 3x. */
1605 gnutls_db_set_cache_expiration(state->session, ssl_session_timeout);
1607 /* Reduce security in favour of increased compatibility, if the admin
1608 decides to make that trade-off. */
1609 if (gnutls_compat_mode)
1611 #if LIBGNUTLS_VERSION_NUMBER >= 0x020104
1612 DEBUG(D_tls) debug_printf("lowering GnuTLS security, compatibility mode\n");
1613 gnutls_session_enable_compatibility_mode(state->session);
1615 DEBUG(D_tls) debug_printf("Unable to set gnutls_compat_mode - GnuTLS version too old\n");
1619 *caller_state = state;
1625 /*************************************************
1626 * Extract peer information *
1627 *************************************************/
1629 static const uschar *
1630 cipher_stdname_kcm(gnutls_kx_algorithm_t kx, gnutls_cipher_algorithm_t cipher,
1631 gnutls_mac_algorithm_t mac)
1634 gnutls_kx_algorithm_t kx_i;
1635 gnutls_cipher_algorithm_t cipher_i;
1636 gnutls_mac_algorithm_t mac_i;
1639 gnutls_cipher_suite_info(i, cs_id, &kx_i, &cipher_i, &mac_i, NULL);
1641 if (kx_i == kx && cipher_i == cipher && mac_i == mac)
1642 return cipher_stdname(cs_id[0], cs_id[1]);
1648 /* Called from both server and client code.
1649 Only this is allowed to set state->peerdn and state->have_set_peerdn
1650 and we use that to detect double-calls.
1652 NOTE: the state blocks last while the TLS connection is up, which is fine
1653 for logging in the server side, but for the client side, we log after teardown
1654 in src/deliver.c. While the session is up, we can twist about states and
1655 repoint tls_* globals, but those variables used for logging or other variable
1656 expansion that happens _after_ delivery need to have a longer life-time.
1658 So for those, we get the data from POOL_PERM; the re-invoke guard keeps us from
1659 doing this more than once per generation of a state context. We set them in
1660 the state context, and repoint tls_* to them. After the state goes away, the
1661 tls_* copies of the pointers remain valid and client delivery logging is happy.
1663 tls_certificate_verified is a BOOL, so the tls_peerdn and tls_cipher issues
1667 state exim_gnutls_state_st *
1668 errstr pointer to error string
1670 Returns: OK/DEFER/FAIL
1674 peer_status(exim_gnutls_state_st * state, uschar ** errstr)
1676 gnutls_session_t session = state->session;
1677 const gnutls_datum_t * cert_list;
1679 unsigned int cert_list_size = 0;
1680 gnutls_protocol_t protocol;
1681 gnutls_cipher_algorithm_t cipher;
1682 gnutls_kx_algorithm_t kx;
1683 gnutls_mac_algorithm_t mac;
1684 gnutls_certificate_type_t ct;
1685 gnutls_x509_crt_t crt;
1689 if (state->have_set_peerdn)
1691 state->have_set_peerdn = TRUE;
1693 state->peerdn = NULL;
1696 cipher = gnutls_cipher_get(session);
1697 protocol = gnutls_protocol_get_version(session);
1698 mac = gnutls_mac_get(session);
1700 #ifdef GNUTLS_TLS1_3
1701 protocol >= GNUTLS_TLS1_3 ? 0 :
1703 gnutls_kx_get(session);
1705 old_pool = store_pool;
1707 tls_support * tlsp = state->tlsp;
1708 store_pool = POOL_PERM;
1710 #ifdef SUPPORT_GNUTLS_SESS_DESC
1713 uschar * s = US gnutls_session_get_desc(session), c;
1715 /* Nikos M suggests we use this by preference. It returns like:
1716 (TLS1.3)-(ECDHE-SECP256R1)-(RSA-PSS-RSAE-SHA256)-(AES-256-GCM)
1718 For partial back-compat, put a colon after the TLS version, replace the
1719 )-( grouping with __, replace in-group - with _ and append the :keysize. */
1721 /* debug_printf("peer_status: gnutls_session_get_desc %s\n", s); */
1723 for (s++; (c = *s) && c != ')'; s++) g = string_catn(g, s, 1);
1724 g = string_catn(g, US":", 1);
1725 if (*s) s++; /* now on _ between groups */
1728 for (*++s && ++s; (c = *s) && c != ')'; s++) g = string_catn(g, c == '-' ? US"_" : s, 1);
1729 /* now on ) closing group */
1730 if ((c = *s) && *++s == '-') g = string_catn(g, US"__", 2);
1731 /* now on _ between groups */
1733 g = string_catn(g, US":", 1);
1734 g = string_cat(g, string_sprintf("%d", (int) gnutls_cipher_get_key_size(cipher) * 8));
1735 state->ciphersuite = string_from_gstring(g);
1738 state->ciphersuite = string_sprintf("%s:%s:%d",
1739 gnutls_protocol_get_name(protocol),
1740 gnutls_cipher_suite_get_name(kx, cipher, mac),
1741 (int) gnutls_cipher_get_key_size(cipher) * 8);
1743 /* I don't see a way that spaces could occur, in the current GnuTLS
1744 code base, but it was a concern in the old code and perhaps older GnuTLS
1745 releases did return "TLS 1.0"; play it safe, just in case. */
1747 for (uschar * p = state->ciphersuite; *p; p++) if (isspace(*p)) *p = '-';
1750 /* debug_printf("peer_status: ciphersuite %s\n", state->ciphersuite); */
1752 tlsp->cipher = state->ciphersuite;
1753 tlsp->bits = gnutls_cipher_get_key_size(cipher) * 8;
1755 tlsp->cipher_stdname = cipher_stdname_kcm(kx, cipher, mac);
1757 store_pool = old_pool;
1760 cert_list = gnutls_certificate_get_peers(session, &cert_list_size);
1762 if (!cert_list || cert_list_size == 0)
1764 DEBUG(D_tls) debug_printf("TLS: no certificate from peer (%p & %d)\n",
1765 cert_list, cert_list_size);
1766 if (state->verify_requirement >= VERIFY_REQUIRED)
1767 return tls_error(US"certificate verification failed",
1768 US"no certificate received from peer", state->host, errstr);
1772 if ((ct = gnutls_certificate_type_get(session)) != GNUTLS_CRT_X509)
1774 const uschar * ctn = US gnutls_certificate_type_get_name(ct);
1776 debug_printf("TLS: peer cert not X.509 but instead \"%s\"\n", ctn);
1777 if (state->verify_requirement >= VERIFY_REQUIRED)
1778 return tls_error(US"certificate verification not possible, unhandled type",
1779 ctn, state->host, errstr);
1783 #define exim_gnutls_peer_err(Label) \
1785 if (rc != GNUTLS_E_SUCCESS) \
1787 DEBUG(D_tls) debug_printf("TLS: peer cert problem: %s: %s\n", \
1788 (Label), gnutls_strerror(rc)); \
1789 if (state->verify_requirement >= VERIFY_REQUIRED) \
1790 return tls_error_gnu((Label), rc, state->host, errstr); \
1795 rc = import_cert(&cert_list[0], &crt);
1796 exim_gnutls_peer_err(US"cert 0");
1798 state->tlsp->peercert = state->peercert = crt;
1801 rc = gnutls_x509_crt_get_dn(crt, NULL, &sz);
1802 if (rc != GNUTLS_E_SHORT_MEMORY_BUFFER)
1804 exim_gnutls_peer_err(US"getting size for cert DN failed");
1805 return FAIL; /* should not happen */
1807 dn_buf = store_get_perm(sz, TRUE); /* tainted */
1808 rc = gnutls_x509_crt_get_dn(crt, CS dn_buf, &sz);
1809 exim_gnutls_peer_err(US"failed to extract certificate DN [gnutls_x509_crt_get_dn(cert 0)]");
1811 state->peerdn = dn_buf;
1814 #undef exim_gnutls_peer_err
1820 /*************************************************
1821 * Verify peer certificate *
1822 *************************************************/
1824 /* Called from both server and client code.
1825 *Should* be using a callback registered with
1826 gnutls_certificate_set_verify_function() to fail the handshake if we dislike
1827 the peer information, but that's too new for some OSes.
1830 state exim_gnutls_state_st *
1831 errstr where to put an error message
1834 FALSE if the session should be rejected
1835 TRUE if the cert is okay or we just don't care
1839 verify_certificate(exim_gnutls_state_st * state, uschar ** errstr)
1844 DEBUG(D_tls) debug_printf("TLS: checking peer certificate\n");
1846 rc = peer_status(state, errstr);
1848 if (state->verify_requirement == VERIFY_NONE)
1851 if (rc != OK || !state->peerdn)
1853 verify = GNUTLS_CERT_INVALID;
1854 *errstr = US"certificate not supplied";
1860 if (state->verify_requirement == VERIFY_DANE && state->host)
1862 /* Using dane_verify_session_crt() would be easy, as it does it all for us
1863 including talking to a DNS resolver. But we want to do that bit ourselves
1864 as the testsuite intercepts and fakes its own DNS environment. */
1869 const gnutls_datum_t * certlist =
1870 gnutls_certificate_get_peers(state->session, &lsize);
1871 int usage = tls_out.tlsa_usage;
1873 # ifdef GNUTLS_BROKEN_DANE_VALIDATION
1874 /* Split the TLSA records into two sets, TA and EE selectors. Run the
1875 dane-verification separately so that we know which selector verified;
1876 then we know whether to do name-verification (needed for TA but not EE). */
1878 if (usage == ((1<<DANESSL_USAGE_DANE_TA) | (1<<DANESSL_USAGE_DANE_EE)))
1879 { /* a mixed-usage bundle */
1884 for(nrec = 0; state->dane_data_len[nrec]; ) nrec++;
1887 dd = store_get(nrec * sizeof(uschar *), FALSE);
1888 ddl = store_get(nrec * sizeof(int), FALSE);
1891 if ((rc = dane_state_init(&s, 0)))
1894 for (usage = DANESSL_USAGE_DANE_EE;
1895 usage >= DANESSL_USAGE_DANE_TA; usage--)
1896 { /* take records with this usage */
1897 for (j = i = 0; i < nrec; i++)
1898 if (state->dane_data[i][0] == usage)
1900 dd[j] = state->dane_data[i];
1901 ddl[j++] = state->dane_data_len[i];
1908 if ((rc = dane_raw_tlsa(s, &r, (char * const *)dd, ddl, 1, 0)))
1911 if ((rc = dane_verify_crt_raw(s, certlist, lsize,
1912 gnutls_certificate_type_get(state->session),
1914 usage == DANESSL_USAGE_DANE_EE
1915 ? DANE_VFLAG_ONLY_CHECK_EE_USAGE : 0,
1919 debug_printf("TLSA record problem: %s\n", dane_strerror(rc));
1921 else if (verify == 0) /* verification passed */
1929 if (rc) goto tlsa_prob;
1934 if ( (rc = dane_state_init(&s, 0))
1935 || (rc = dane_raw_tlsa(s, &r, state->dane_data, state->dane_data_len,
1937 || (rc = dane_verify_crt_raw(s, certlist, lsize,
1938 gnutls_certificate_type_get(state->session),
1940 # ifdef GNUTLS_BROKEN_DANE_VALIDATION
1941 usage == (1 << DANESSL_USAGE_DANE_EE)
1942 ? DANE_VFLAG_ONLY_CHECK_EE_USAGE : 0,
1951 if (verify != 0) /* verification failed */
1954 (void) dane_verification_status_print(verify, &str, 0);
1955 *errstr = US str.data; /* don't bother to free */
1959 # ifdef GNUTLS_BROKEN_DANE_VALIDATION
1960 /* If a TA-mode TLSA record was used for verification we must additionally
1961 verify the cert name (but not the CA chain). For EE-mode, skip it. */
1963 if (usage & (1 << DANESSL_USAGE_DANE_EE))
1966 state->peer_dane_verified = state->peer_cert_verified = TRUE;
1969 # ifdef GNUTLS_BROKEN_DANE_VALIDATION
1970 /* Assume that the name on the A-record is the one that should be matching
1971 the cert. An alternate view is that the domain part of the email address
1972 is also permissible. */
1974 if (gnutls_x509_crt_check_hostname(state->tlsp->peercert,
1975 CS state->host->name))
1977 state->peer_dane_verified = state->peer_cert_verified = TRUE;
1982 #endif /*SUPPORT_DANE*/
1984 rc = gnutls_certificate_verify_peers2(state->session, &verify);
1987 /* Handle the result of verification. INVALID is set if any others are. */
1989 if (rc < 0 || verify & (GNUTLS_CERT_INVALID|GNUTLS_CERT_REVOKED))
1991 state->peer_cert_verified = FALSE;
1994 #ifdef GNUTLS_CERT_VFY_STATUS_PRINT
1999 if (gnutls_certificate_verification_status_print(verify,
2000 gnutls_certificate_type_get(state->session), &txt, 0)
2001 == GNUTLS_E_SUCCESS)
2003 debug_printf("%s\n", txt.data);
2004 gnutls_free(txt.data);
2008 *errstr = verify & GNUTLS_CERT_REVOKED
2009 ? US"certificate revoked" : US"certificate invalid";
2013 debug_printf("TLS certificate verification failed (%s): peerdn=\"%s\"\n",
2014 *errstr, state->peerdn ? state->peerdn : US"<unset>");
2016 if (state->verify_requirement >= VERIFY_REQUIRED)
2019 debug_printf("TLS verify failure overridden (host in tls_try_verify_hosts)\n");
2024 /* Client side, check the server's certificate name versus the name on the
2025 A-record for the connection we made. What to do for server side - what name
2026 to use for client? We document that there is no such checking for server
2029 if ( state->exp_tls_verify_cert_hostnames
2030 && !gnutls_x509_crt_check_hostname(state->tlsp->peercert,
2031 CS state->exp_tls_verify_cert_hostnames)
2035 debug_printf("TLS certificate verification failed: cert name mismatch\n");
2036 if (state->verify_requirement >= VERIFY_REQUIRED)
2041 state->peer_cert_verified = TRUE;
2042 DEBUG(D_tls) debug_printf("TLS certificate verified: peerdn=\"%s\"\n",
2043 state->peerdn ? state->peerdn : US"<unset>");
2047 state->tlsp->peerdn = state->peerdn;
2052 *errstr = string_sprintf("TLSA record problem: %s",
2053 rc == DANE_E_REQUESTED_DATA_NOT_AVAILABLE ? "none usable" : dane_strerror(rc));
2057 gnutls_alert_send(state->session, GNUTLS_AL_FATAL, GNUTLS_A_BAD_CERTIFICATE);
2064 /* ------------------------------------------------------------------------ */
2067 /* Logging function which can be registered with
2068 * gnutls_global_set_log_function()
2069 * gnutls_global_set_log_level() 0..9
2071 #if EXIM_GNUTLS_LIBRARY_LOG_LEVEL >= 0
2073 exim_gnutls_logger_cb(int level, const char *message)
2075 size_t len = strlen(message);
2078 DEBUG(D_tls) debug_printf("GnuTLS<%d> empty debug message\n", level);
2081 DEBUG(D_tls) debug_printf("GnuTLS<%d>: %s%s", level, message,
2082 message[len-1] == '\n' ? "" : "\n");
2087 /* Called after client hello, should handle SNI work.
2088 This will always set tls_sni (state->received_sni) if available,
2089 and may trigger presenting different certificates,
2090 if state->trigger_sni_changes is TRUE.
2092 Should be registered with
2093 gnutls_handshake_set_post_client_hello_function()
2095 "This callback must return 0 on success or a gnutls error code to terminate the
2098 For inability to get SNI information, we return 0.
2099 We only return non-zero if re-setup failed.
2100 Only used for server-side TLS.
2104 exim_sni_handling_cb(gnutls_session_t session)
2106 char sni_name[MAX_HOST_LEN];
2107 size_t data_len = MAX_HOST_LEN;
2108 exim_gnutls_state_st *state = &state_server;
2109 unsigned int sni_type;
2111 uschar * dummy_errstr;
2113 rc = gnutls_server_name_get(session, sni_name, &data_len, &sni_type, 0);
2114 if (rc != GNUTLS_E_SUCCESS)
2117 if (rc == GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE)
2118 debug_printf("TLS: no SNI presented in handshake.\n");
2120 debug_printf("TLS failure: gnutls_server_name_get(): %s [%d]\n",
2121 gnutls_strerror(rc), rc);
2125 if (sni_type != GNUTLS_NAME_DNS)
2127 DEBUG(D_tls) debug_printf("TLS: ignoring SNI of unhandled type %u\n", sni_type);
2131 /* We now have a UTF-8 string in sni_name */
2132 old_pool = store_pool;
2133 store_pool = POOL_PERM;
2134 state->received_sni = string_copy_taint(US sni_name, TRUE);
2135 store_pool = old_pool;
2137 /* We set this one now so that variable expansions below will work */
2138 state->tlsp->sni = state->received_sni;
2140 DEBUG(D_tls) debug_printf("Received TLS SNI \"%s\"%s\n", sni_name,
2141 state->trigger_sni_changes ? "" : " (unused for certificate selection)");
2143 if (!state->trigger_sni_changes)
2146 if ((rc = tls_expand_session_files(state, &dummy_errstr)) != OK)
2148 /* If the setup of certs/etc failed before handshake, TLS would not have
2149 been offered. The best we can do now is abort. */
2150 return GNUTLS_E_APPLICATION_ERROR_MIN;
2153 rc = tls_set_remaining_x509(state, &dummy_errstr);
2154 if (rc != OK) return GNUTLS_E_APPLICATION_ERROR_MIN;
2161 #if !defined(DISABLE_OCSP)
2164 server_ocsp_stapling_cb(gnutls_session_t session, void * ptr,
2165 gnutls_datum_t * ocsp_response)
2168 DEBUG(D_tls) debug_printf("OCSP stapling callback: %s\n", US ptr);
2170 if ((ret = gnutls_load_file(ptr, ocsp_response)) < 0)
2172 DEBUG(D_tls) debug_printf("Failed to load ocsp stapling file %s\n",
2174 tls_in.ocsp = OCSP_NOT_RESP;
2175 return GNUTLS_E_NO_CERTIFICATE_STATUS;
2178 tls_in.ocsp = OCSP_VFY_NOT_TRIED;
2185 #ifndef DISABLE_EVENT
2187 We use this callback to get observability and detail-level control
2188 for an exim TLS connection (either direction), raising a tls:cert event
2189 for each cert in the chain presented by the peer. Any event
2190 can deny verification.
2192 Return 0 for the handshake to continue or non-zero to terminate.
2196 verify_cb(gnutls_session_t session)
2198 const gnutls_datum_t * cert_list;
2199 unsigned int cert_list_size = 0;
2200 gnutls_x509_crt_t crt;
2203 exim_gnutls_state_st * state = gnutls_session_get_ptr(session);
2205 if ((cert_list = gnutls_certificate_get_peers(session, &cert_list_size)))
2206 while (cert_list_size--)
2208 if ((rc = import_cert(&cert_list[cert_list_size], &crt)) != GNUTLS_E_SUCCESS)
2210 DEBUG(D_tls) debug_printf("TLS: peer cert problem: depth %d: %s\n",
2211 cert_list_size, gnutls_strerror(rc));
2215 state->tlsp->peercert = crt;
2216 if ((yield = event_raise(state->event_action,
2217 US"tls:cert", string_sprintf("%d", cert_list_size))))
2219 log_write(0, LOG_MAIN,
2220 "SSL verify denied by event-action: depth=%d: %s",
2221 cert_list_size, yield);
2222 return 1; /* reject */
2224 state->tlsp->peercert = NULL;
2234 ddump(gnutls_datum_t * d)
2236 gstring * g = string_get((d->size+1) * 2);
2237 uschar * s = d->data;
2238 for (unsigned i = d->size; i > 0; i--, s++)
2240 g = string_catn(g, US "0123456789abcdef" + (*s >> 4), 1);
2241 g = string_catn(g, US "0123456789abcdef" + (*s & 0xf), 1);
2247 post_handshake_debug(exim_gnutls_state_st * state)
2249 #ifdef SUPPORT_GNUTLS_SESS_DESC
2250 debug_printf("%s\n", gnutls_session_get_desc(state->session));
2252 #ifdef SUPPORT_GNUTLS_KEYLOG
2254 # ifdef EXIM_HAVE_TLS1_3
2255 if (gnutls_protocol_get_version(state->session) < GNUTLS_TLS1_3)
2260 gnutls_datum_t c, s;
2262 /* we only want the client random and the master secret */
2263 gnutls_session_get_random(state->session, &c, &s);
2264 gnutls_session_get_master_secret(state->session, &s);
2267 debug_printf("CLIENT_RANDOM %.*s %.*s\n", (int)gc->ptr, gc->s, (int)gs->ptr, gs->s);
2270 debug_printf("To get keying info for TLS1.3 is hard:\n"
2271 " set environment variable SSLKEYLOGFILE to a filename writable by uid exim\n"
2272 " add SSLKEYLOGFILE to keep_environment in the exim config\n"
2273 " run exim as root\n"
2274 " if using sudo, add SSLKEYLOGFILE to env_keep in /etc/sudoers\n"
2275 " (works for TLS1.2 also, and saves cut-paste into file)\n");
2280 #ifdef EXPERIMENTAL_TLS_RESUME
2282 tls_server_ticket_cb(gnutls_session_t sess, u_int htype, unsigned when,
2283 unsigned incoming, const gnutls_datum_t * msg)
2285 DEBUG(D_tls) debug_printf("newticket cb\n");
2286 tls_in.resumption |= RESUME_CLIENT_REQUESTED;
2291 tls_server_resume_prehandshake(exim_gnutls_state_st * state)
2293 /* Should the server offer session resumption? */
2294 tls_in.resumption = RESUME_SUPPORTED;
2295 if (verify_check_host(&tls_resumption_hosts) == OK)
2298 /* GnuTLS appears to not do ticket overlap, but does emit a fresh ticket when
2299 an offered resumption is unacceptable. We lose one resumption per ticket
2300 lifetime, and sessions cannot be indefinitely re-used. There seems to be no
2301 way (3.6.7) of changing the default number of 2 TLS1.3 tickets issued, but at
2302 least they go out in a single packet. */
2304 if (!(rc = gnutls_session_ticket_enable_server(state->session,
2305 &server_sessticket_key)))
2306 tls_in.resumption |= RESUME_SERVER_TICKET;
2309 debug_printf("enabling session tickets: %s\n", US gnutls_strerror(rc));
2311 /* Try to tell if we see a ticket request */
2312 gnutls_handshake_set_hook_function(state->session,
2313 GNUTLS_HANDSHAKE_ANY, GNUTLS_HOOK_POST, tls_server_hook_cb);
2318 tls_server_resume_posthandshake(exim_gnutls_state_st * state)
2320 if (gnutls_session_resumption_requested(state->session))
2322 /* This tells us the client sent a full ticket. We use a
2323 callback on session-ticket request, elsewhere, to tell
2324 if a client asked for a ticket. */
2326 tls_in.resumption |= RESUME_CLIENT_SUGGESTED;
2327 DEBUG(D_tls) debug_printf("client requested resumption\n");
2329 if (gnutls_session_is_resumed(state->session))
2331 tls_in.resumption |= RESUME_USED;
2332 DEBUG(D_tls) debug_printf("Session resumed\n");
2336 /* ------------------------------------------------------------------------ */
2337 /* Exported functions */
2342 /*************************************************
2343 * Start a TLS session in a server *
2344 *************************************************/
2346 /* This is called when Exim is running as a server, after having received
2347 the STARTTLS command. It must respond to that command, and then negotiate
2351 require_ciphers list of allowed ciphers or NULL
2352 errstr pointer to error string
2354 Returns: OK on success
2355 DEFER for errors before the start of the negotiation
2356 FAIL for errors during the negotiation; the server can't
2361 tls_server_start(const uschar * require_ciphers, uschar ** errstr)
2364 exim_gnutls_state_st * state = NULL;
2366 /* Check for previous activation */
2367 if (tls_in.active.sock >= 0)
2369 tls_error(US"STARTTLS received after TLS started", US "", NULL, errstr);
2370 smtp_printf("554 Already in TLS\r\n", FALSE);
2374 /* Initialize the library. If it fails, it will already have logged the error
2375 and sent an SMTP response. */
2377 DEBUG(D_tls) debug_printf("initialising GnuTLS as a server\n");
2379 if ((rc = tls_init(NULL, tls_certificate, tls_privatekey,
2380 NULL, tls_verify_certificates, tls_crl,
2381 require_ciphers, &state, &tls_in, errstr)) != OK) return rc;
2383 #ifdef EXPERIMENTAL_TLS_RESUME
2384 tls_server_resume_prehandshake(state);
2387 /* If this is a host for which certificate verification is mandatory or
2388 optional, set up appropriately. */
2390 if (verify_check_host(&tls_verify_hosts) == OK)
2393 debug_printf("TLS: a client certificate will be required.\n");
2394 state->verify_requirement = VERIFY_REQUIRED;
2395 gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_REQUIRE);
2397 else if (verify_check_host(&tls_try_verify_hosts) == OK)
2400 debug_printf("TLS: a client certificate will be requested but not required.\n");
2401 state->verify_requirement = VERIFY_OPTIONAL;
2402 gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_REQUEST);
2407 debug_printf("TLS: a client certificate will not be requested.\n");
2408 state->verify_requirement = VERIFY_NONE;
2409 gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_IGNORE);
2412 #ifndef DISABLE_EVENT
2415 state->event_action = event_action;
2416 gnutls_session_set_ptr(state->session, state);
2417 gnutls_certificate_set_verify_function(state->x509_cred, verify_cb);
2421 /* Register SNI handling; always, even if not in tls_certificate, so that the
2422 expansion variable $tls_sni is always available. */
2424 gnutls_handshake_set_post_client_hello_function(state->session,
2425 exim_sni_handling_cb);
2427 /* Set context and tell client to go ahead, except in the case of TLS startup
2428 on connection, where outputting anything now upsets the clients and tends to
2429 make them disconnect. We need to have an explicit fflush() here, to force out
2430 the response. Other smtp_printf() calls do not need it, because in non-TLS
2431 mode, the fflush() happens when smtp_getc() is called. */
2433 if (!state->tlsp->on_connect)
2435 smtp_printf("220 TLS go ahead\r\n", FALSE);
2439 /* Now negotiate the TLS session. We put our own timer on it, since it seems
2440 that the GnuTLS library doesn't.
2441 From 3.1.0 there is gnutls_handshake_set_timeout() - but it requires you
2442 to set (and clear down afterwards) up a pull-timeout callback function that does
2443 a select, so we're no better off unless avoiding signals becomes an issue. */
2445 gnutls_transport_set_ptr2(state->session,
2446 (gnutls_transport_ptr_t)(long) fileno(smtp_in),
2447 (gnutls_transport_ptr_t)(long) fileno(smtp_out));
2448 state->fd_in = fileno(smtp_in);
2449 state->fd_out = fileno(smtp_out);
2451 sigalrm_seen = FALSE;
2452 if (smtp_receive_timeout > 0) ALARM(smtp_receive_timeout);
2454 rc = gnutls_handshake(state->session);
2455 while (rc == GNUTLS_E_AGAIN || rc == GNUTLS_E_INTERRUPTED && !sigalrm_seen);
2458 if (rc != GNUTLS_E_SUCCESS)
2460 /* It seems that, except in the case of a timeout, we have to close the
2461 connection right here; otherwise if the other end is running OpenSSL it hangs
2462 until the server times out. */
2466 tls_error(US"gnutls_handshake", US"timed out", NULL, errstr);
2467 gnutls_db_remove_session(state->session);
2471 tls_error_gnu(US"gnutls_handshake", rc, NULL, errstr);
2472 (void) gnutls_alert_send_appropriate(state->session, rc);
2473 gnutls_deinit(state->session);
2474 gnutls_certificate_free_credentials(state->x509_cred);
2476 shutdown(state->fd_out, SHUT_WR);
2477 for (int i = 1024; fgetc(smtp_in) != EOF && i > 0; ) i--; /* drain skt */
2478 (void)fclose(smtp_out);
2479 (void)fclose(smtp_in);
2480 smtp_out = smtp_in = NULL;
2486 #ifdef EXPERIMENTAL_TLS_RESUME
2487 tls_server_resume_posthandshake(state);
2490 DEBUG(D_tls) post_handshake_debug(state);
2492 /* Verify after the fact */
2494 if (!verify_certificate(state, errstr))
2496 if (state->verify_requirement != VERIFY_OPTIONAL)
2498 (void) tls_error(US"certificate verification failed", *errstr, NULL, errstr);
2502 debug_printf("TLS: continuing on only because verification was optional, after: %s\n",
2506 /* Sets various Exim expansion variables; always safe within server */
2508 extract_exim_vars_from_tls_state(state);
2510 /* TLS has been set up. Adjust the input functions to read via TLS,
2511 and initialize appropriately. */
2513 state->xfer_buffer = store_malloc(ssl_xfer_buffer_size);
2515 receive_getc = tls_getc;
2516 receive_getbuf = tls_getbuf;
2517 receive_get_cache = tls_get_cache;
2518 receive_ungetc = tls_ungetc;
2519 receive_feof = tls_feof;
2520 receive_ferror = tls_ferror;
2521 receive_smtp_buffered = tls_smtp_buffered;
2530 tls_client_setup_hostname_checks(host_item * host, exim_gnutls_state_st * state,
2531 smtp_transport_options_block * ob)
2533 if (verify_check_given_host(CUSS &ob->tls_verify_cert_hostnames, host) == OK)
2535 state->exp_tls_verify_cert_hostnames =
2537 string_domain_utf8_to_alabel(host->name, NULL);
2542 debug_printf("TLS: server cert verification includes hostname: \"%s\".\n",
2543 state->exp_tls_verify_cert_hostnames);
2551 /* Given our list of RRs from the TLSA lookup, build a lookup block in
2552 GnuTLS-DANE's preferred format. Hang it on the state str for later
2553 use in DANE verification.
2555 We point at the dnsa data not copy it, so it must remain valid until
2556 after verification is done.*/
2559 dane_tlsa_load(exim_gnutls_state_st * state, dns_answer * dnsa)
2563 const char ** dane_data;
2564 int * dane_data_len;
2567 for (dns_record * rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS); rr;
2568 rr = dns_next_rr(dnsa, &dnss, RESET_NEXT)
2569 ) if (rr->type == T_TLSA) i++;
2571 dane_data = store_get(i * sizeof(uschar *), FALSE);
2572 dane_data_len = store_get(i * sizeof(int), FALSE);
2575 for (dns_record * rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS); rr;
2576 rr = dns_next_rr(dnsa, &dnss, RESET_NEXT)
2577 ) if (rr->type == T_TLSA && rr->size > 3)
2579 const uschar * p = rr->data;
2580 /*XXX need somehow to mark rr and its data as tainted. Doues this mean copying it? */
2581 uint8_t usage = p[0], sel = p[1], type = p[2];
2584 debug_printf("TLSA: %d %d %d size %d\n", usage, sel, type, rr->size);
2586 if ( (usage != DANESSL_USAGE_DANE_TA && usage != DANESSL_USAGE_DANE_EE)
2587 || (sel != 0 && sel != 1)
2592 case 0: /* Full: cannot check at present */
2594 case 1: if (rr->size != 3 + 256/8) continue; /* sha2-256 */
2596 case 2: if (rr->size != 3 + 512/8) continue; /* sha2-512 */
2601 tls_out.tlsa_usage |= 1<<usage;
2602 dane_data[i] = CS p;
2603 dane_data_len[i++] = rr->size;
2606 if (!i) return FALSE;
2608 dane_data[i] = NULL;
2609 dane_data_len[i] = 0;
2611 state->dane_data = (char * const *)dane_data;
2612 state->dane_data_len = dane_data_len;
2619 #ifdef EXPERIMENTAL_TLS_RESUME
2620 /* On the client, get any stashed session for the given IP from hints db
2621 and apply it to the ssl-connection for attempted resumption. Although
2622 there is a gnutls_session_ticket_enable_client() interface it is
2623 documented as unnecessary (as of 3.6.7) as "session tickets are emabled
2624 by deafult". There seems to be no way to disable them, so even hosts not
2625 enabled by the transport option will be sent a ticket request. We will
2626 however avoid storing and retrieving session information. */
2629 tls_retrieve_session(tls_support * tlsp, gnutls_session_t session,
2630 host_item * host, smtp_transport_options_block * ob)
2632 tlsp->resumption = RESUME_SUPPORTED;
2633 if (verify_check_given_host(CUSS &ob->tls_resumption_hosts, host) == OK)
2635 dbdata_tls_session * dt;
2637 open_db dbblock, * dbm_file;
2640 debug_printf("check for resumable session for %s\n", host->address);
2641 tlsp->host_resumable = TRUE;
2642 tlsp->resumption |= RESUME_CLIENT_REQUESTED;
2643 if ((dbm_file = dbfn_open(US"tls", O_RDONLY, &dbblock, FALSE, FALSE)))
2645 /* Key for the db is the IP. We'd like to filter the retrieved session
2646 for ticket advisory expiry, but 3.6.1 seems to give no access to that */
2648 if ((dt = dbfn_read_with_length(dbm_file, host->address, &len)))
2649 if (!(rc = gnutls_session_set_data(session,
2650 CUS dt->session, (size_t)len - sizeof(dbdata_tls_session))))
2652 DEBUG(D_tls) debug_printf("good session\n");
2653 tlsp->resumption |= RESUME_CLIENT_SUGGESTED;
2655 else DEBUG(D_tls) debug_printf("setting session resumption data: %s\n",
2656 US gnutls_strerror(rc));
2657 dbfn_close(dbm_file);
2664 tls_save_session(tls_support * tlsp, gnutls_session_t session, const host_item * host)
2666 /* TLS 1.2 - we get both the callback and the direct posthandshake call,
2667 but this flag is not set until the second. TLS 1.3 it's the other way about.
2668 Keep both calls as the session data cannot be extracted before handshake
2671 if (gnutls_session_get_flags(session) & GNUTLS_SFLAGS_SESSION_TICKET)
2676 DEBUG(D_tls) debug_printf("server offered session ticket\n");
2677 tlsp->ticket_received = TRUE;
2678 tlsp->resumption |= RESUME_SERVER_TICKET;
2680 if (tlsp->host_resumable)
2681 if (!(rc = gnutls_session_get_data2(session, &tkt)))
2683 open_db dbblock, * dbm_file;
2684 int dlen = sizeof(dbdata_tls_session) + tkt.size;
2685 dbdata_tls_session * dt = store_get(dlen, TRUE);
2687 DEBUG(D_tls) debug_printf("session data size %u\n", (unsigned)tkt.size);
2688 memcpy(dt->session, tkt.data, tkt.size);
2689 gnutls_free(tkt.data);
2691 if ((dbm_file = dbfn_open(US"tls", O_RDWR, &dbblock, FALSE, FALSE)))
2693 /* key for the db is the IP */
2694 dbfn_delete(dbm_file, host->address);
2695 dbfn_write(dbm_file, host->address, dt, dlen);
2696 dbfn_close(dbm_file);
2699 debug_printf("wrote session db (len %u)\n", (unsigned)dlen);
2703 debug_printf("extract session data: %s\n", US gnutls_strerror(rc));
2708 /* With a TLS1.3 session, the ticket(s) are not seen until
2709 the first data read is attempted. And there's often two of them.
2710 Pick them up with this callback. We are also called for 1.2
2714 tls_client_ticket_cb(gnutls_session_t sess, u_int htype, unsigned when,
2715 unsigned incoming, const gnutls_datum_t * msg)
2717 exim_gnutls_state_st * state = gnutls_session_get_ptr(sess);
2718 tls_support * tlsp = state->tlsp;
2720 DEBUG(D_tls) debug_printf("newticket cb\n");
2722 if (!tlsp->ticket_received)
2723 tls_save_session(tlsp, sess, state->host);
2729 tls_client_resume_prehandshake(exim_gnutls_state_st * state,
2730 tls_support * tlsp, host_item * host,
2731 smtp_transport_options_block * ob)
2733 gnutls_session_set_ptr(state->session, state);
2734 gnutls_handshake_set_hook_function(state->session,
2735 GNUTLS_HANDSHAKE_NEW_SESSION_TICKET, GNUTLS_HOOK_POST, tls_client_ticket_cb);
2737 tls_retrieve_session(tlsp, state->session, host, ob);
2741 tls_client_resume_posthandshake(exim_gnutls_state_st * state,
2742 tls_support * tlsp, host_item * host)
2744 if (gnutls_session_is_resumed(state->session))
2746 DEBUG(D_tls) debug_printf("Session resumed\n");
2747 tlsp->resumption |= RESUME_USED;
2750 tls_save_session(tlsp, state->session, host);
2752 #endif /* EXPERIMENTAL_TLS_RESUME */
2755 /*************************************************
2756 * Start a TLS session in a client *
2757 *************************************************/
2759 /* Called from the smtp transport after STARTTLS has been accepted.
2762 cctx connection context
2763 conn_args connection details
2764 cookie datum for randomness (not used)
2765 tlsp record details of channel configuration here; must be non-NULL
2766 errstr error string pointer
2768 Returns: TRUE for success with TLS session context set in smtp context,
2773 tls_client_start(client_conn_ctx * cctx, smtp_connect_args * conn_args,
2774 void * cookie ARG_UNUSED,
2775 tls_support * tlsp, uschar ** errstr)
2777 host_item * host = conn_args->host; /* for msgs and option-tests */
2778 transport_instance * tb = conn_args->tblock; /* always smtp or NULL */
2779 smtp_transport_options_block * ob = tb
2780 ? (smtp_transport_options_block *)tb->options_block
2781 : &smtp_transport_option_defaults;
2783 exim_gnutls_state_st * state = NULL;
2784 uschar * cipher_list = NULL;
2786 #ifndef DISABLE_OCSP
2788 verify_check_given_host(CUSS &ob->hosts_require_ocsp, host) == OK;
2789 BOOL request_ocsp = require_ocsp ? TRUE
2790 : verify_check_given_host(CUSS &ob->hosts_request_ocsp, host) == OK;
2793 DEBUG(D_tls) debug_printf("initialising GnuTLS as a client on fd %d\n", cctx->sock);
2796 /* If dane is flagged, have either request or require dane for this host, and
2797 a TLSA record found. Therefore, dane verify required. Which implies cert must
2798 be requested and supplied, dane verify must pass, and cert verify irrelevant
2799 (incl. hostnames), and (caller handled) require_tls */
2801 if (conn_args->dane && ob->dane_require_tls_ciphers)
2803 /* not using expand_check_tlsvar because not yet in state */
2804 if (!expand_check(ob->dane_require_tls_ciphers, US"dane_require_tls_ciphers",
2805 &cipher_list, errstr))
2807 cipher_list = cipher_list && *cipher_list
2808 ? ob->dane_require_tls_ciphers : ob->tls_require_ciphers;
2813 cipher_list = ob->tls_require_ciphers;
2815 if (tls_init(host, ob->tls_certificate, ob->tls_privatekey,
2816 ob->tls_sni, ob->tls_verify_certificates, ob->tls_crl,
2817 cipher_list, &state, tlsp, errstr) != OK)
2821 int dh_min_bits = ob->tls_dh_min_bits;
2822 if (dh_min_bits < EXIM_CLIENT_DH_MIN_MIN_BITS)
2825 debug_printf("WARNING: tls_dh_min_bits far too low,"
2826 " clamping %d up to %d\n",
2827 dh_min_bits, EXIM_CLIENT_DH_MIN_MIN_BITS);
2828 dh_min_bits = EXIM_CLIENT_DH_MIN_MIN_BITS;
2831 DEBUG(D_tls) debug_printf("Setting D-H prime minimum"
2832 " acceptable bits to %d\n",
2834 gnutls_dh_set_prime_bits(state->session, dh_min_bits);
2837 /* Stick to the old behaviour for compatibility if tls_verify_certificates is
2838 set but both tls_verify_hosts and tls_try_verify_hosts are unset. Check only
2839 the specified host patterns if one of them is defined */
2842 if (conn_args->dane && dane_tlsa_load(state, &conn_args->tlsa_dnsa))
2845 debug_printf("TLS: server certificate DANE required.\n");
2846 state->verify_requirement = VERIFY_DANE;
2847 gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_REQUIRE);
2851 if ( ( state->exp_tls_verify_certificates
2852 && !ob->tls_verify_hosts
2853 && (!ob->tls_try_verify_hosts || !*ob->tls_try_verify_hosts)
2855 || verify_check_given_host(CUSS &ob->tls_verify_hosts, host) == OK
2858 tls_client_setup_hostname_checks(host, state, ob);
2860 debug_printf("TLS: server certificate verification required.\n");
2861 state->verify_requirement = VERIFY_REQUIRED;
2862 gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_REQUIRE);
2864 else if (verify_check_given_host(CUSS &ob->tls_try_verify_hosts, host) == OK)
2866 tls_client_setup_hostname_checks(host, state, ob);
2868 debug_printf("TLS: server certificate verification optional.\n");
2869 state->verify_requirement = VERIFY_OPTIONAL;
2870 gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_REQUEST);
2875 debug_printf("TLS: server certificate verification not required.\n");
2876 state->verify_requirement = VERIFY_NONE;
2877 gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_IGNORE);
2880 #ifndef DISABLE_OCSP
2881 /* supported since GnuTLS 3.1.3 */
2884 DEBUG(D_tls) debug_printf("TLS: will request OCSP stapling\n");
2885 if ((rc = gnutls_ocsp_status_request_enable_client(state->session,
2886 NULL, 0, NULL)) != OK)
2888 tls_error_gnu(US"cert-status-req", rc, state->host, errstr);
2891 tlsp->ocsp = OCSP_NOT_RESP;
2895 #ifdef EXPERIMENTAL_TLS_RESUME
2896 tls_client_resume_prehandshake(state, tlsp, host, ob);
2899 #ifndef DISABLE_EVENT
2900 if (tb && tb->event_action)
2902 state->event_action = tb->event_action;
2903 gnutls_session_set_ptr(state->session, state);
2904 gnutls_certificate_set_verify_function(state->x509_cred, verify_cb);
2908 gnutls_transport_set_ptr(state->session, (gnutls_transport_ptr_t)(long) cctx->sock);
2909 state->fd_in = cctx->sock;
2910 state->fd_out = cctx->sock;
2912 DEBUG(D_tls) debug_printf("about to gnutls_handshake\n");
2913 /* There doesn't seem to be a built-in timeout on connection. */
2915 sigalrm_seen = FALSE;
2916 ALARM(ob->command_timeout);
2918 rc = gnutls_handshake(state->session);
2919 while (rc == GNUTLS_E_AGAIN || rc == GNUTLS_E_INTERRUPTED && !sigalrm_seen);
2922 if (rc != GNUTLS_E_SUCCESS)
2926 gnutls_alert_send(state->session, GNUTLS_AL_FATAL, GNUTLS_A_USER_CANCELED);
2927 tls_error(US"gnutls_handshake", US"timed out", state->host, errstr);
2930 tls_error_gnu(US"gnutls_handshake", rc, state->host, errstr);
2934 DEBUG(D_tls) post_handshake_debug(state);
2938 if (!verify_certificate(state, errstr))
2940 tls_error(US"certificate verification failed", *errstr, state->host, errstr);
2944 #ifndef DISABLE_OCSP
2949 gnutls_datum_t stapling;
2950 gnutls_ocsp_resp_t resp;
2951 gnutls_datum_t printed;
2955 # ifdef GNUTLS_OCSP_STATUS_REQUEST_GET2
2956 (rc = gnutls_ocsp_status_request_get2(state->session, idx, &stapling)) == 0;
2958 (rc = gnutls_ocsp_status_request_get(state->session, &stapling)) == 0;
2961 if ( (rc= gnutls_ocsp_resp_init(&resp)) == 0
2962 && (rc= gnutls_ocsp_resp_import(resp, &stapling)) == 0
2963 && (rc= gnutls_ocsp_resp_print(resp, GNUTLS_OCSP_PRINT_COMPACT, &printed)) == 0
2966 debug_printf("%.4096s", printed.data);
2967 gnutls_free(printed.data);
2970 (void) tls_error_gnu(US"ocsp decode", rc, state->host, errstr);
2972 (void) tls_error_gnu(US"ocsp decode", rc, state->host, errstr);
2975 if (gnutls_ocsp_status_request_is_checked(state->session, 0) == 0)
2977 tlsp->ocsp = OCSP_FAILED;
2978 tls_error(US"certificate status check failed", NULL, state->host, errstr);
2984 DEBUG(D_tls) debug_printf("Passed OCSP checking\n");
2985 tlsp->ocsp = OCSP_VFIED;
2990 #ifdef EXPERIMENTAL_TLS_RESUME
2991 tls_client_resume_posthandshake(state, tlsp, host);
2994 /* Sets various Exim expansion variables; may need to adjust for ACL callouts */
2996 extract_exim_vars_from_tls_state(state);
2998 cctx->tls_ctx = state;
3005 /*************************************************
3006 * Close down a TLS session *
3007 *************************************************/
3009 /* This is also called from within a delivery subprocess forked from the
3010 daemon, to shut down the TLS library, without actually doing a shutdown (which
3011 would tamper with the TLS session in the parent process).
3014 ct_ctx client context pointer, or NULL for the one global server context
3015 shutdown 1 if TLS close-alert is to be sent,
3016 2 if also response to be waited for
3022 tls_close(void * ct_ctx, int shutdown)
3024 exim_gnutls_state_st * state = ct_ctx ? ct_ctx : &state_server;
3025 tls_support * tlsp = state->tlsp;
3027 if (!tlsp || tlsp->active.sock < 0) return; /* TLS was not active */
3031 DEBUG(D_tls) debug_printf("tls_close(): shutting down TLS%s\n",
3032 shutdown > 1 ? " (with response-wait)" : "");
3035 gnutls_bye(state->session, shutdown > 1 ? GNUTLS_SHUT_RDWR : GNUTLS_SHUT_WR);
3039 if (!ct_ctx) /* server */
3041 receive_getc = smtp_getc;
3042 receive_getbuf = smtp_getbuf;
3043 receive_get_cache = smtp_get_cache;
3044 receive_ungetc = smtp_ungetc;
3045 receive_feof = smtp_feof;
3046 receive_ferror = smtp_ferror;
3047 receive_smtp_buffered = smtp_buffered;
3050 gnutls_deinit(state->session);
3051 gnutls_certificate_free_credentials(state->x509_cred);
3053 tlsp->active.sock = -1;
3054 tlsp->active.tls_ctx = NULL;
3055 /* Leave bits, peercert, cipher, peerdn, certificate_verified set, for logging */
3056 tls_channelbinding_b64 = NULL;
3059 if (state->xfer_buffer) store_free(state->xfer_buffer);
3060 memcpy(state, &exim_gnutls_state_init, sizeof(exim_gnutls_state_init));
3067 tls_refill(unsigned lim)
3069 exim_gnutls_state_st * state = &state_server;
3072 DEBUG(D_tls) debug_printf("Calling gnutls_record_recv(%p, %p, %u)\n",
3073 state->session, state->xfer_buffer, ssl_xfer_buffer_size);
3075 sigalrm_seen = FALSE;
3076 if (smtp_receive_timeout > 0) ALARM(smtp_receive_timeout);
3079 inbytes = gnutls_record_recv(state->session, state->xfer_buffer,
3080 MIN(ssl_xfer_buffer_size, lim));
3081 while (inbytes == GNUTLS_E_AGAIN);
3083 if (smtp_receive_timeout > 0) ALARM_CLR(0);
3085 if (had_command_timeout) /* set by signal handler */
3086 smtp_command_timeout_exit(); /* does not return */
3087 if (had_command_sigterm)
3088 smtp_command_sigterm_exit();
3089 if (had_data_timeout)
3090 smtp_data_timeout_exit();
3091 if (had_data_sigint)
3092 smtp_data_sigint_exit();
3094 /* Timeouts do not get this far. A zero-byte return appears to mean that the
3095 TLS session has been closed down, not that the socket itself has been closed
3096 down. Revert to non-TLS handling. */
3100 DEBUG(D_tls) debug_printf("Got tls read timeout\n");
3101 state->xfer_error = TRUE;
3105 else if (inbytes == 0)
3107 DEBUG(D_tls) debug_printf("Got TLS_EOF\n");
3108 tls_close(NULL, TLS_NO_SHUTDOWN);
3112 /* Handle genuine errors */
3114 else if (inbytes < 0)
3116 DEBUG(D_tls) debug_printf("%s: err from gnutls_record_recv\n", __FUNCTION__);
3117 record_io_error(state, (int) inbytes, US"recv", NULL);
3118 state->xfer_error = TRUE;
3121 #ifndef DISABLE_DKIM
3122 dkim_exim_verify_feed(state->xfer_buffer, inbytes);
3124 state->xfer_buffer_hwm = (int) inbytes;
3125 state->xfer_buffer_lwm = 0;
3129 /*************************************************
3130 * TLS version of getc *
3131 *************************************************/
3133 /* This gets the next byte from the TLS input buffer. If the buffer is empty,
3134 it refills the buffer via the GnuTLS reading function.
3135 Only used by the server-side TLS.
3137 This feeds DKIM and should be used for all message-body reads.
3139 Arguments: lim Maximum amount to read/buffer
3140 Returns: the next character or EOF
3144 tls_getc(unsigned lim)
3146 exim_gnutls_state_st * state = &state_server;
3148 if (state->xfer_buffer_lwm >= state->xfer_buffer_hwm)
3149 if (!tls_refill(lim))
3150 return state->xfer_error ? EOF : smtp_getc(lim);
3152 /* Something in the buffer; return next uschar */
3154 return state->xfer_buffer[state->xfer_buffer_lwm++];
3158 tls_getbuf(unsigned * len)
3160 exim_gnutls_state_st * state = &state_server;
3164 if (state->xfer_buffer_lwm >= state->xfer_buffer_hwm)
3165 if (!tls_refill(*len))
3167 if (!state->xfer_error) return smtp_getbuf(len);
3172 if ((size = state->xfer_buffer_hwm - state->xfer_buffer_lwm) > *len)
3174 buf = &state->xfer_buffer[state->xfer_buffer_lwm];
3175 state->xfer_buffer_lwm += size;
3184 #ifndef DISABLE_DKIM
3185 exim_gnutls_state_st * state = &state_server;
3186 int n = state->xfer_buffer_hwm - state->xfer_buffer_lwm;
3188 dkim_exim_verify_feed(state->xfer_buffer+state->xfer_buffer_lwm, n);
3194 tls_could_read(void)
3196 return state_server.xfer_buffer_lwm < state_server.xfer_buffer_hwm
3197 || gnutls_record_check_pending(state_server.session) > 0;
3203 /*************************************************
3204 * Read bytes from TLS channel *
3205 *************************************************/
3207 /* This does not feed DKIM, so if the caller uses this for reading message body,
3208 then the caller must feed DKIM.
3211 ct_ctx client context pointer, or NULL for the one global server context
3215 Returns: the number of bytes read
3216 -1 after a failed read, including EOF
3220 tls_read(void * ct_ctx, uschar *buff, size_t len)
3222 exim_gnutls_state_st * state = ct_ctx ? ct_ctx : &state_server;
3228 if (state->xfer_buffer_lwm < state->xfer_buffer_hwm)
3230 debug_printf("*** PROBABLY A BUG *** " \
3231 "tls_read() called with data in the tls_getc() buffer, %d ignored\n",
3232 state->xfer_buffer_hwm - state->xfer_buffer_lwm);
3235 debug_printf("Calling gnutls_record_recv(%p, %p, " SIZE_T_FMT ")\n",
3236 state->session, buff, len);
3239 inbytes = gnutls_record_recv(state->session, buff, len);
3240 while (inbytes == GNUTLS_E_AGAIN);
3242 if (inbytes > 0) return inbytes;
3245 DEBUG(D_tls) debug_printf("Got TLS_EOF\n");
3249 DEBUG(D_tls) debug_printf("%s: err from gnutls_record_recv\n", __FUNCTION__);
3250 record_io_error(state, (int)inbytes, US"recv", NULL);
3259 /*************************************************
3260 * Write bytes down TLS channel *
3261 *************************************************/
3265 ct_ctx client context pointer, or NULL for the one global server context
3268 more more data expected soon
3270 Returns: the number of bytes after a successful write,
3271 -1 after a failed write
3275 tls_write(void * ct_ctx, const uschar * buff, size_t len, BOOL more)
3279 exim_gnutls_state_st * state = ct_ctx ? ct_ctx : &state_server;
3281 static BOOL corked = FALSE;
3283 if (more && !corked) gnutls_record_cork(state->session);
3286 DEBUG(D_tls) debug_printf("%s(%p, " SIZE_T_FMT "%s)\n", __FUNCTION__,
3287 buff, left, more ? ", more" : "");
3291 DEBUG(D_tls) debug_printf("gnutls_record_send(SSL, %p, " SIZE_T_FMT ")\n",
3295 outbytes = gnutls_record_send(state->session, buff, left);
3296 while (outbytes == GNUTLS_E_AGAIN);
3298 DEBUG(D_tls) debug_printf("outbytes=" SSIZE_T_FMT "\n", outbytes);
3301 DEBUG(D_tls) debug_printf("%s: gnutls_record_send err\n", __FUNCTION__);
3302 record_io_error(state, outbytes, US"send", NULL);
3307 record_io_error(state, 0, US"send", US"TLS channel closed on write");
3318 debug_printf("Whoops! Wrote more bytes (" SIZE_T_FMT ") than INT_MAX\n",
3326 if (!more) (void) gnutls_record_uncork(state->session, 0);
3337 /*************************************************
3338 * Random number generation *
3339 *************************************************/
3341 /* Pseudo-random number generation. The result is not expected to be
3342 cryptographically strong but not so weak that someone will shoot themselves
3343 in the foot using it as a nonce in input in some email header scheme or
3344 whatever weirdness they'll twist this into. The result should handle fork()
3345 and avoid repeating sequences. OpenSSL handles that for us.
3349 Returns a random number in range [0, max-1]
3352 #ifdef HAVE_GNUTLS_RND
3354 vaguely_random_number(int max)
3358 uschar smallbuf[sizeof(r)];
3363 needed_len = sizeof(r);
3364 /* Don't take 8 times more entropy than needed if int is 8 octets and we were
3365 asked for a number less than 10. */
3367 for (r = max, i = 0; r; ++i)
3373 i = gnutls_rnd(GNUTLS_RND_NONCE, smallbuf, needed_len);
3376 DEBUG(D_all) debug_printf("gnutls_rnd() failed, using fallback.\n");
3377 return vaguely_random_number_fallback(max);
3380 for (uschar * p = smallbuf; needed_len; --needed_len, ++p)
3383 /* We don't particularly care about weighted results; if someone wants
3384 * smooth distribution and cares enough then they should submit a patch then. */
3387 #else /* HAVE_GNUTLS_RND */
3389 vaguely_random_number(int max)
3391 return vaguely_random_number_fallback(max);
3393 #endif /* HAVE_GNUTLS_RND */
3398 /*************************************************
3399 * Let tls_require_ciphers be checked at startup *
3400 *************************************************/
3402 /* The tls_require_ciphers option, if set, must be something which the
3405 Returns: NULL on success, or error message
3409 tls_validate_require_cipher(void)
3412 uschar *expciphers = NULL;
3413 gnutls_priority_t priority_cache;
3415 uschar * dummy_errstr;
3417 #define validate_check_rc(Label) do { \
3418 if (rc != GNUTLS_E_SUCCESS) { if (exim_gnutls_base_init_done) gnutls_global_deinit(); \
3419 return string_sprintf("%s failed: %s", (Label), gnutls_strerror(rc)); } } while (0)
3420 #define return_deinit(Label) do { gnutls_global_deinit(); return (Label); } while (0)
3422 if (exim_gnutls_base_init_done)
3423 log_write(0, LOG_MAIN|LOG_PANIC,
3424 "already initialised GnuTLS, Exim developer bug");
3426 #ifdef HAVE_GNUTLS_PKCS11
3427 if (!gnutls_allow_auto_pkcs11)
3429 rc = gnutls_pkcs11_init(GNUTLS_PKCS11_FLAG_MANUAL, NULL);
3430 validate_check_rc(US"gnutls_pkcs11_init");
3433 rc = gnutls_global_init();
3434 validate_check_rc(US"gnutls_global_init()");
3435 exim_gnutls_base_init_done = TRUE;
3437 if (!(tls_require_ciphers && *tls_require_ciphers))
3438 return_deinit(NULL);
3440 if (!expand_check(tls_require_ciphers, US"tls_require_ciphers", &expciphers,
3442 return_deinit(US"failed to expand tls_require_ciphers");
3444 if (!(expciphers && *expciphers))
3445 return_deinit(NULL);
3448 debug_printf("tls_require_ciphers expands to \"%s\"\n", expciphers);
3450 rc = gnutls_priority_init(&priority_cache, CS expciphers, &errpos);
3451 validate_check_rc(string_sprintf(
3452 "gnutls_priority_init(%s) failed at offset %ld, \"%.8s..\"",
3453 expciphers, errpos - CS expciphers, errpos));
3455 #undef return_deinit
3456 #undef validate_check_rc
3457 gnutls_global_deinit();
3465 /*************************************************
3466 * Report the library versions. *
3467 *************************************************/
3469 /* See a description in tls-openssl.c for an explanation of why this exists.
3471 Arguments: a FILE* to print the results to
3476 tls_version_report(FILE *f)
3478 fprintf(f, "Library version: GnuTLS: Compile: %s\n"
3481 gnutls_check_version(NULL));
3484 #endif /*!MACRO_PREDEF*/
3487 /* End of tls-gnu.c */